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Abstract:

A heat exchanger core optimization method is provided for a heat
exchanger door which resides at an air inlet or outlet side of an
electronics rack, and includes an air-to-coolant heat exchanger with a
heat exchanger core. The core includes a first coolant channel coupled to
a coolant inlet manifold downstream from a second coolant channel, and
the first channel has a shorter channel length than the second channel.
Further, coolant channels of the core are coupled to provide counter-flow
cooling of an airflow passing across the core. The core optimization
method determines at least one combination of parameters that optimize
for a particular application at least two performance metrics of the heat
exchanger. This method includes obtaining performance metrics for
boundary condition(s) of possible heat exchanger configurations with
different variable parameters to determine a combination of parameters
that optimize the performance metrics for the heat exchanger.

Claims:

1. A method comprising: determining at least one combination of
parameters that optimizes at least two performance metrics of a heat
exchanger, the determining comprising: ascertaining at least two variable
parameters of the heat exchanger; ascertaining at least one boundary
condition for the heat exchanger; obtaining, by at least one processor,
at least two performance metrics for the at least one boundary condition
for at least two possible heat exchanger configurations of the heat
exchanger that include different combinations of the at least one
non-variable parameter and at least two variable parameters; and using
the at least one processor in determining which of the at least two
possible heat exchanger configurations optimizes the at least two
performance metrics for the at least one boundary condition, the
determining facilitating ascertaining at least one combination of the at
least two variable parameters that optimizes the at least two performance
metrics of the heat exchanger.

2. The method of claim 1, wherein the heat exchanger comprises an
air-to-coolant heat exchanger, and wherein the at least two performance
metrics include at least two of: heat removal of the at least two
possible heat exchanger configurations; air side pressure drop of the at
least two possible heat exchanger configurations; coolant side pressure
drop of the at least two possible heat exchanger configurations; weight
of the heat exchanger; and depth of the heat exchanger.

3. The method of claim 1, further comprising constructing at least a
portion of the at least two possible heat exchanger configurations and
performing measurements thereon and generating the at least two
performance metrics for the at least one boundary condition for the at
least two possible heat exchanger configurations.

4. The method of claim 1, wherein the at least one processor determines
the at least two performance metrics for the at least one boundary
condition for the at least two possible heat exchanger configurations and
the at least two variable parameters.

5. The method of claim 1, wherein the at least one processor utilizes the
at least one boundary condition, the different combinations of the at
least two variable parameters, and the at least two performance metrics
in producing a visual indication of a relationship of the different
combinations of the at least two variable parameters with the boundary
condition(s), and the at least two performance metrics, and thereby
facilitates determining at least one combination of the at least two
variable parameters that optimizes the at least two performance metrics
for the at least one boundary condition of the heat exchanger.

6. The method of claim 1, wherein the at least one processor utilizes the
at least one boundary condition, the different combinations of the at
least two variable parameters, and the corresponding at least two
performance metrics in determining at least one combination of the at
least two variable parameters that optimizes the at least two performance
metrics for the at least one boundary condition of the heat exchanger.

7. The method of claim 1, further including obtaining at least one
limiting performance metric for the at least two possible heat exchanger
configurations, and filtering out a possible heat exchanger configuration
of the at least two possible heat exchanger configurations that includes
at least one limiting performance metric for the at least two boundary
conditions outside of an acceptable threshold before the using of the at
least one processor in determining which of the at least two possible
heat exchanger configurations optimizes the at least two performance
metrics for the at least one boundary condition.

8. A method comprising: determining at least one combination of
parameters that optimizes performance metrics of an air-to-coolant heat
exchanger, the determining comprising: ascertaining at least one
non-variable parameter and at least two variable parameters of the
air-to-coolant heat exchanger; ascertaining at least two boundary
conditions for the heat exchanger; obtaining, by at least one processor,
at least two performance metrics, for the at least two boundary
conditions, of at least two possible heat exchanger configurations that
include different combinations of the at least one non-variable parameter
and the at least two variable parameters; using the at least one
processor in determining whether a possible heat exchanger configuration
of the at least two possible heat exchanger configurations has acceptable
performance metrics for the at least two boundary conditions, thereby
facilitating determining at least one combination of the at least one
non-variable parameter and the at least two variable parameters that
provides desired performance metrics, for the at least two boundary
conditions, of the air-to-coolant heat exchanger; and wherein the at
least two performance metrics include a heat removal rate from airflow
across the air-to-coolant heat exchanger and an air side pressure drop
across the air-to-coolant heat exchanger.

9. The method of claim 8, further comprising constructing at least a
portion of the at least two possible heat exchanger configurations and
performing measurements thereon and generating the at least two
performance metrics, for the at least two boundary conditions, of the at
least two possible heat exchanger configurations.

10. The method of claim 8, wherein the at least one processor determines
the at least two performance metrics, for the at least two boundary
conditions, for the at least two possible heat exchanger configurations
and the at least one non-variable parameter, and the at least two
variable parameters.

11. The method of claim 8, wherein the at least one processor utilizes
the at least two boundary conditions, the different combinations of the
at least one non-variable parameter and the at least two variable
parameters, and the at least two performance metrics in producing a
visual indication of a relationship of the different combinations of the
at least one non-variable parameter and the at least two variable
parameters with the boundary conditions, and the at least two performance
metrics, and thereby facilitates determining at least one combination of
the at least one non-variable parameter and the at least two variable
parameters that optimizes the at least two performance metrics, for the
at least two boundary conditions, of the air-to-coolant heat exchanger.

12. The method of claim 8, wherein the at least one processor utilizes
the at least two boundary conditions, the different combinations of the
at least one non-variable parameter and the at least two variable
parameters, and the corresponding at least two performance metrics in
determining at least one combination of the at least one non-variable
parameter and the at least two variable parameters that optimizes the at
least two performance metrics, for the at least two boundary conditions,
of the air-to-coolant heat exchanger.

13. The method of claim 8, further including obtaining at least one
limiting performance metric for the at least two possible heat exchanger
configurations, and filtering out a possible heat exchanger configuration
of the at least two possible heat exchanger configurations that includes
at least one limiting performance metric for the at least two boundary
conditions outside of an acceptable threshold before the using of the at
least one processor in determining which of the at least two possible
heat exchanger configurations optimizes the at least two performance
metrics for the at least two boundary conditions.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. Ser. No. 13/443,094,
filed Apr. 10, 2012, and entitled "Process for Optimizing a Heat
Exchanger Configuration", and which is hereby incorporated herein by
reference in its entirety.

BACKGROUND

[0002] The power dissipation of integrated circuit chips, and the modules
containing the chips, continues to increase in order to achieve increases
in processor performance. This trend poses a cooling challenge at both
module and system levels. Increased airflow rates are needed to
effectively cool high-powered modules, and to limit the temperature of
the air that is exhausted into the computer center.

[0003] In many large server applications, processors, along with their
associated electronics (e.g., memory, disk drives, power supplies, etc.),
are packaged in removable drawer configurations stacked within a rack or
frame. In other cases, the electronics may be in fixed locations within
the rack or frame. Typically, the components are cooled by air moving in
parallel airflow paths, usually front-to-back, impelled by one or more
air-moving devices (e.g., fans or blowers). In some cases, it may be
possible to handle increased power dissipation within a single drawer by
providing greater airflow, through the use of a more powerful air-moving
device, or by increasing the rotational speed (i.e., RPMs) of an existing
air-moving device.

[0004] The sensible heat load carried by the air exiting the rack is
stressing the capability of the room air-conditioning to effectively
handle the load. This is especially true for large installations with
"server farms", or large banks of computer racks close together. In such
installations, liquid-cooling (e.g., water-cooling) is an attractive
technology to manage the higher heat fluxes. The liquid absorbs the heat
dissipated by the components/modules in an efficient manner. Typically,
the heat is ultimately transferred from the liquid to an outside
environment.

BRIEF SUMMARY

[0005] The shortcomings of the prior art are overcome and additional
advantages are provided through the provision of a method, which
includes: determining at least one combination of parameters that
optimizes at least two performance metrics of a heat exchanger. The
determining includes: ascertaining at least two variable parameters of
the heat exchanger; ascertaining at least one boundary condition for the
heat exchanger; obtaining, by at least one processor, at least two
performance metrics for the at least one boundary condition for at least
two possible heat exchanger configurations of the heat exchanger that
include different combinations of the at least two variable parameters;
and using the at least one processor in determining which of the at least
two possible heat exchanger configurations optimizes the at least two
performance metrics for the at least one boundary condition, the
determining facilitating ascertaining at least one combination of the at
least two variable parameters that optimizes the at least two performance
metrics of the heat exchanger.

[0006] In another aspect, a method is provided which includes determining
at least one combination of parameters that optimizes performance metrics
of an air-to-coolant heat exchanger. The determining includes:
ascertaining at least one non-variable parameter and at least two
variable parameters of the air-to-coolant heat exchanger; ascertaining at
least two boundary conditions for the heat exchanger; obtaining, by at
least one processor, at least two performance metrics, for the at least
two boundary conditions, of at least two possible heat exchanger
configurations that include different combinations of the at least one
non-variable parameter and the at least two variable parameters; and
using the at least one processor in determining whether a possible heat
exchanger configuration of the at least two possible heat exchanger
configurations has acceptable performance metrics for the at least two
boundary conditions, thereby facilitating determining at least one
combination of the at least one non-variable parameter and the at least
two variable parameters that provides desired performance metrics, for
the at least two boundary conditions, of the air-to-coolant heat
exchanger, wherein the at least two performance metrics includes a heat
removal rate from airflow across the air-to-coolant heat exchanger and an
air side pressure drop across the air-to-coolant heat exchanger.

[0007] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects of the
invention are described in detail herein and are considered a part of the
claimed invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0008] One or more aspects of the present invention are particularly
pointed out and distinctly claimed as examples in the claims at the
conclusion of the specification. The foregoing and other objects,
features, and advantages of the invention are apparent from the following
detailed description taken in conjunction with the accompanying drawings
in which:

[0009]FIG. 1 depicts one embodiment of a raised floor layout of a
computer installation capable of being retrofitted with one or more
air-cooling apparatuses, in accordance with one or more aspects of the
present invention;

[0010]FIG. 2A is a top plan view of one embodiment of an electronics rack
with a heat exchanger door mounted to an air outlet side thereof, and
with extracted heat being rejected to facility coolant via a coolant
distribution unit, in accordance with one or more aspects of the present
invention;

[0011]FIG. 2B is a side elevational view of the electronics rack and heat
exchanger door of FIG. 2A, in accordance with one or more aspects of the
present invention;

[0012]FIG. 3 depicts one embodiment of a data center layout comprising
multiple coolant distribution units providing coolant to a plurality of
electronics racks with air-cooling apparatuses mounted to at least one of
the air inlet sides or air outlet sides thereof, in accordance with one
or more aspects of the present invention;

[0013]FIG. 4 depicts one implementation of a partially assembled heat
exchanger door to be modified, in accordance with one or more aspects of
the present invention;

[0014]FIG. 5A depicts an electronics rack with an air-cooling apparatus
disposed at one of the air outlet side or air inlet side thereof, and
with the heat exchanger door shown in a latched position, in accordance
with one or more aspects of the present invention;

[0015] FIG. 5B depicts the electronics rack and air-cooling apparatus of
FIG. 5A, with the heat exchanger door shown in an unlatched and open
position, in accordance with one or more aspects of the present
invention;

[0016]FIG. 6 depicts an inner side, isometric view of one partial
embodiment of the heat exchanger door of FIGS. 5A & 5B, in accordance
with one or more aspects of the present invention;

[0017]FIG. 7A is a partial cross-sectional plan view of the electronics
rack and air-cooling apparatus of FIGS. 5A-6, shown with the heat
exchanger door latched to the electronics rack, in accordance with one or
more aspects of the present invention;

[0018]FIG. 7B is a partial cross-sectional elevational side view taken
along line 7B-7B in FIG. 7A, and shown with the latch lever of the door
latch mechanism latched to the catch bracket of the air-cooling
apparatus, in accordance with one or more aspects of the present
invention;

[0019]FIG. 7c depicts the partial cross-sectional elevational view of
FIG. 7B, with the latch lever unlatched or disengaged from the catch
bracket to allow opening of the heat exchanger door, in accordance with
one or more aspects of the present invention;

[0020]FIG. 8A is a front isometric view of one embodiment of the door
latch mechanism of FIGS. 7A-7C, in accordance with one or more aspects of
the present invention;

[0021] FIG. 8B is a back isometric view of the door latch mechanism of
FIG. 8A, in accordance with one or more aspects of the present invention;

[0022]FIG. 9 is an isometric view of one embodiment of the catch bracket
of FIGS. 7A-7C of the air-cooling apparatus, in accordance with one or
more aspects of the present invention;

[0023]FIG. 10 is a partial cross-sectional plan view of another
embodiment of a heat exchanger door, configured with an inward-curved or
inward-angled latch edge, in accordance with one or more aspects of the
present invention;

[0024]FIG. 11A is a partially exploded view of one embodiment of a heat
exchanger door assembly, in accordance with one or more aspects of the
present invention;

[0025]FIG. 11B is an enlarged depiction of an upper portion of the
partially exploded door assembly of FIG. 11A, in accordance with one or
more aspects of the present invention;

[0026]FIG. 11c is an enlarged depiction of a lower portion of the
partially exploded door assembly of FIG. 11A, in accordance with one or
more aspects of the present invention;

[0027] FIG. 12A is a front elevational view of the assembly of FIGS. 5A &
5B, with the heat exchanger door coupled to the electronics rack, in
accordance with one or more aspects of the present invention;

[0028]FIG. 12B is a partial cross-sectional plan view of the assembly of
FIG. 12A, taken along line 12B-12B thereof, in accordance with one or
more aspects of the present invention; and

[0029]FIG. 13 is an isometric view of a portion of one embodiment of a
heat exchanger door assembly, illustrating a structural support coupled
to the heat exchanger casing, and defining a tubular door support beam
structure, in accordance with one or more aspects of the present
invention;

[0030]FIG. 14 is a side elevational view of one embodiment of a portion
of a plurality coolant channels and inlet and outlet manifolds of a heat
exchanger configuration, in accordance with one or more aspects of the
present invention;

[0031]FIG. 15 is a side elevational view of another embodiment of a
portion of a plurality coolant channels and inlet and outlet manifolds of
a heat exchanger configuration, in accordance with one or more aspects of
the present invention;

[0032]FIG. 16 is a side elevational view of a further embodiment of a
portion of a plurality coolant channels and inlet and outlet manifolds of
a heat exchanger configuration, in accordance with one or more aspects of
the present invention;

[0033]FIG. 17 depicts a flowchart of one embodiment of a process for
determining a combination of parameters that optimize at least two
performance metrics of a heat exchanger, in accordance with one or more
aspects of the present invention;

[0034]FIG. 18 depicts one example of a computing environment to implement
one or more aspects of the present invention;

[0035]FIG. 19 is a visual representation of performance metrics and heat
exchanger parameters for different heat exchanger configurations with
differing combinations of parameters, in accordance with one or more
aspects of the present invention; and

[0036] FIGS. 20A & 20B are a visual representation of optimum fin
parameters for heat exchanger configurations with differing numbers of
rows of coolant channels, in accordance with one or more aspects of the
present invention.

DETAILED DESCRIPTION

[0037] As used herein, the terms "electronics rack", "rack unit", and
"rack" are used interchangeably, and unless otherwise specified, include
any housing, frame, support structure, compartment, blade server system,
etc., having one or more heat generating components of a computer system
or electronic system, and may be, for example, a stand-alone computer
processor having high, mid or low end processing capability. In one
embodiment, an electronics rack may comprise a portion of an electronic
system, a single electronic system, or multiple electronic systems, for
example, in one or more sub-housings, blades, books, drawers, nodes,
compartments, etc., having one or more heat-generating electronic
components disposed therein. An electronic system within an electronics
rack may be movable or fixed relative to the electronics rack, with the
rack-mounted electronic drawers of a multi-drawer rack unit and blades of
a blade center system being two examples of systems (or subsystems) of an
electronics rack to be cooled.

[0038] Further, as used herein, "air-to-coolant heat exchanger" means any
heat exchange mechanism characterized as described herein through which
coolant can circulate; and includes, one or more discrete air-to-coolant
heat exchangers coupled either in series or in parallel. An
air-to-coolant heat exchanger may comprise, for example, one or more
coolant flow paths, formed of thermally conductive tubings (such as
copper or other tubing) in thermal or mechanical contact with a plurality
of air-cooled cooling fins (such as aluminum or other fins). Unless
otherwise specified, size, configuration and construction of the
air-to-coolant heat exchanger can vary without departing from the scope
of the invention disclosed herein. A "coolant-to-liquid heat exchanger"
may comprise, for example, two or more coolant flow paths, formed of
thermally conductive tubings (such as copper or other tubing) in thermal
or mechanical contact with each other to facilitate conduction of heat
therebetween. Size, configuration and construction of the
coolant-to-liquid heat exchanger can vary without departing from the
scope of the invention disclosed herein. Further, as used herein, "data
center" refers to a computer installation containing one or more
electronics racks, and as a specific example, a data center may include
one or more rows of rack-mounted computing units, such as server units.

[0039] One example of facility coolant and system coolant is water.
However, the concepts disclosed herein are readily adapted to use with
other types of coolant on the facility side and/or on the system side.
For example, one or more of the coolants may comprise a water-glycol
mixture, a brine, a fluorocarbon liquid, a liquid metal, or other similar
coolant, or a refrigerant, while still maintaining the advantages and
unique features of the present invention. Further, the term "coolant"
refers to any liquid or gas, or combination thereof, used to remove heat,
in accordance with the structures and concepts disclosed herein.

[0040] Reference is made below to the drawings, which are not drawn to
scale to facilitate an understanding of the invention, wherein the same
reference numbers used throughout different figures designate the same or
similar components.

[0041] As shown in FIG. 1, in a raised floor layout of an air cooled
computer installation or data center 100, multiple electronics racks 110
may be disposed in one or more rows. A computer installation such as
depicted in FIG. 1 may house several hundred, or even several thousand
processors. In the arrangement of FIG. 1, chilled air enters the computer
room via floor vents from a supply air plenum 145 defined between a
raised floor 140 and a base or sub-floor 165 of the room. Cooled air is
taken in through louvered covers at the front, or air inlet sides 120, of
the electronics racks and expelled through the back, or air outlet sides
130, of the electronics racks. Each electronics rack 110 may have one or
more air-moving devices (e.g., fans or blowers) to provide forced
inlet-to-outlet airflow to cool the electronic components within the
rack. Supply air plenum 145 provides conditioned and cooled air to the
air-inlet sides of the electronics racks via perforated floor tiles 160
disposed (in one embodiment) in a "cold" air aisle of the data center.
The conditioned and cooled air is supplied to plenum 145 by one or more
air-conditioning units 150, which may also be disposed within data center
100. Room air is taken into each air-conditioning unit 150 near an upper
portion thereof. In the depicted embodiment, this room air comprises in
part exhausted air from the "hot" air aisles of the data center defined
by opposing air outlet sides 130 of the electronics racks 110.

[0042] Due to ever increasing airflow requirements through electronics
racks, and the limits of air distribution within the typical computer
room installation, recirculation problems within the room may occur.
Recirculation can occur because the conditioned air supplied through the
floor tiles may only be a fraction of the airflow rate forced through the
electronics racks by the air moving devices disposed within the racks.
This can be due, for example, to limitations on the tile sizes (or
diffuser flow rates). The remaining fraction of the supply of inlet side
air may be made up by ambient room air through recirculation, for
example, from the air outlet side of the rack unit to the air inlet side.
This recirculating flow is often very complex in nature, and can lead to
significantly higher rack inlet temperatures than might be expected.

[0043] Recirculation of hot exhaust air from the hot aisle of the computer
room installation to the cold aisle can be detrimental to the performance
and reliability of the computer system(s) or electronic system(s) within
the rack(s). Data center equipment is typically designed to operate with
rack air inlet temperatures in the 15-35° C. range. For a raised
floor layout such as depicted in FIG. 1, however, temperatures can range
from 15-20° C. at the lower portion of the rack, close to the cool
air floor vents, to as much as 32-42° C. at the upper portion of
the electronics rack, where hot air can form a self-sustaining
recirculation loop. Since the allowable rack heat load is limited by the
rack inlet air temperature at the "hot" part, this temperature
distribution correlates to an inefficient utilization of available air
conditioning capability. Computer installation equipment almost always
represents a high capital investment to the customer. Thus, it is of
significant importance, from a product reliability and performance view
point, and from a customer satisfaction and business perspective, to
achieve a substantially uniform temperature across the air inlet side of
the rack unit.

[0044] Referring collectively to FIGS. 2A & 2B, these figures depict one
embodiment of a cooled electronic system, generally denoted 200, which
includes an electronics rack 210 having an inlet door 220 and an outlet
door 230. The inlet and outlet doors have openings to allow for the
ingress and egress of air 201, respectively, through the air inlet side
and air outlet side of electronics rack 210. The system further includes
at least one air-moving device 212 for moving air across at least one
electronic system or component 214 disposed within the electronics rack.
Located within outlet door 230 is an air-to-coolant heat exchanger 240
across which the inlet-to-outlet airflow 201 through the electronics rack
passes. As shown in FIG. 2A, a system coolant loop 245 couples
air-to-coolant heat exchanger 240 to a coolant distribution unit 250.
Coolant distribution unit 250 is used to buffer the air-to-coolant heat
exchanger from facility coolant in a facility coolant loop 260.
Air-to-coolant heat exchanger 240 removes heat from the exhausted
inlet-to-outlet airflow 201 through the electronics rack via circulating
system coolant, for rejection in coolant distribution unit 250 to
facility coolant in facility coolant loop 260, for example, via a
coolant-to-liquid heat exchanger 252 disposed therein. By way of example,
such a system is described in U.S. Pat. No. 7,385,810 B2, issued Jun. 10,
2008, and entitled "Apparatus and Method for Facilitating Cooling of an
Electronics Rack Employing a Heat Exchange Assembly Mounted to an Outlet
Door Cover of the Electronics Rack". This cooling apparatus can
advantageously reduce heat load on the existing air-conditioning unit(s)
within the data center, and facilitates cooling of electronics racks by
cooling (in one embodiment) the air egressing from the electronics rack
and thus cooling any air recirculating to the air inlet side thereof

[0045] In one implementation, inlet and outlet coolant manifolds of the
door-mounted, air-to-coolant heat exchanger are also mounted within the
heat exchanger door and are coupled to coolant supply and return lines
disposed, for example, beneath a raised floor. Alternatively, overhead
system coolant supply and return lines might be provided for the
air-to-coolant heat exchangers. In such an embodiment, system coolant
would enter and exit the respective coolant inlet and outlet manifolds
from the top of the rack door, for example, using flexible coolant supply
and return hoses, which may be at least partially looped and sized to
facilitate opening and closing of the heat exchanger door. Additionally,
structures may be provided at the ends of the hoses to relive stress at
the hose ends, which would result from opening or closing of the door.

[0046]FIG. 3 is a plan view of one embodiment of a data center, generally
denoted 300, with cooled electronic systems comprising door-mounted,
air-to-coolant heat exchangers, such as disclosed herein. Data center 300
includes a plurality of rows of electronics racks 210, each of which
includes (by way of example only) an inlet door 220 at the air inlet
side, and a hinged heat exchanger door 230 at the air outlet side, such
as described above in connection with the embodiment of FIGS. 2A & 2B. In
this embodiment, each heat exchanger door 230 comprises an air-to-coolant
heat exchanger and system coolant inlet and outlet manifolds. Multiple
coolant conditioning units 250, which function in part as coolant pumping
units, are disposed within the data center (possibly along with one or
more air-conditioning units (not shown)). By way of example only, each
pumping unit may form a system coolant distribution subsystem with one
row of a plurality of electronics racks. Each pumping unit includes a
coolant-to-liquid heat exchanger where heat is transferred from a system
coolant loop to a facility coolant loop. In operation, chilled facility
coolant, such as water, is received via a facility coolant supply line
301, and returned via a facility coolant return line 302. System coolant,
such as water, is provided via a system coolant supply manifold 310
extending below the respective row of electronics racks, and is returned
via a system coolant return manifold 320 also extending below the
respective row of electronics racks. In one embodiment, the system
coolant supply and return manifolds 310, 320 are hard-plumbed within the
data center, for example, within an air supply plenum of the data center,
and may be preconfigured to align under and include branch lines (or
hoses) extending towards the electronics racks in a respective row of
racks.

[0047]FIG. 4 depicts one version of a heat exchanger door 230 for
mounting to the air outlet side of an electronics rack, such as described
above in connection with FIGS. 2A-3. This embodiment is described in
detail in the above-noted U.S. Pat. No. 7,385,810 B2, and represents one
version of an outlet door 230 with an air-to-coolant heat exchanger 240
mounted therein. In this embodiment, a coolant inlet manifold 410 and
coolant outlet manifold 420 are provided along a hinge edge 401, which is
configured to facilitate hinged mounting of the outlet door to an
electronics rack. The coolant inlet and outlet manifolds 410, 420 further
include couplings, such as quick connect couplings 411, 421 within the
outlet door that are aligned vertically with the coolant inlet and outlet
manifolds.

[0048] A heat exchanger door, such as depicted in FIG. 4, comprises a
cooling device, and replaces (for example) a door of an electronics rack.
When incorporated as an outlet door, the heat exchanger door does not
provide any direct cooling to the electronic components within the
electronics rack, but rather facilitates a reduction in the exhaust air
temperature into the data center that may re-circulate to the air inlet
side, as well as reduces the heat load to be removed by, for example, the
computer room air-conditioning units, and thus, facilitates management of
the heat load within the data center. Depending on the implementation,
since the temperature of air leaving the electronics rack via a heat
exchanger door, such as as disclosed herein, can be as cold as or colder
than the air entering the electronics rack, usage of the heat exchanger
door proposed herein may decrease or even eliminate the need for computer
room air-conditioners within the data center.

[0049] Advantages of using a heat exchanger door, especially configured,
such as disclosed herein, include: the ability to support a much higher
power-rack load than can otherwise be supported by traditional
air-cooling of the data center alone, which is generally limited to about
10-15 kW/rack for the majority of data centers; eliminates the
uncomfortable hot aisle/cold aisle data center floor configuration;
eliminates the need for hot aisle and/or cold aisle containment; has
significant energy efficiency, that is, as compared with conventional
air-cooling, where the typical air-cooled data center must pay for the
electrical power used by the blowers and the computer room
air-conditioner to force the chilled air under the floor and through the
perforated tiles on the floor, to the inlet sides of the electronics
racks; utilizes a coolant (such as water) which can result in a 4×
to 10× reduction in the cooling cost of a data center; solves the
hot spot issues within a data center due to recirculation of exhaust air;
is a passive apparatus, requiring no power at the heat exchanger door,
and depending on the implementation, requires no fans or control elements
which would need to be purchased or replaced if failed; and creates no
extra noise within the data center environment.

[0050] In view of the significant importance, from a product reliability
and performance viewpoint, and from a customer satisfaction and business
perspective, to achieve a substantially uniform temperature across the
air inlet side of the electronics rack, disclosed herein are various
enhancements to the air-cooling apparatus and heat exchanger door
configuration described above in connection with FIGS. 2A-4.

[0051] There are two primary objectives in designing a heat exchanger
door, which are in opposition to each other. These objectives are:

[0052] 1. A desire to maximize the amount of heat which can be removed
from the air stream. In a simplest form, this can be accomplished by
increasing the fin density of the heat exchanger core.

[0053] 2. A desire
to minimize the air-side pressure drop across the heat exchanger. Since
in certain embodiments disclosed herein the heat exchanger door does not
have any fans of its own, the fans in the existing electronics rack need
to provide enough flow to counteract the impedance of airflow through the
electronic system(s) (e.g., server(s)), as well as through the heat
exchanger door. For a fixed fan speed, the net airflow rate delivered by
the fans will decrease as the impedance of the heat exchanger door
increases. This decrease in airflow might trigger thermal sensors to
signal for more airflow by increasing the speed (RPMs), power
consumption, and thus noise of the fans or other air-moving devices. If
the air-moving devices are already at their maximum speed, they are
unable to increase speed, and increased component temperatures will
result. In its simplest form, decreasing the air-side pressure drop of
the heat exchanger door can be accomplished by decreasing the fin density
of the heat exchanger core. Therefore, maintaining a very low airflow
impedance for the heat exchanger door is important to a commercially
successful implementation.

[0054] Since power consumption continues to dramatically increase within
electronics rack, provided herein are various enhancements to the
above-described heat exchanger door, which result, for example, in a
2× improvement in heat removal compared to the outlet door version
depicted in FIG. 4, without increasing the air-side pressure drop
(impedance). Other objectives in designing a heat exchanger door include:
minimizing coolant-side flow rate and pressure drop requirements to
minimize pumping costs (operating expenses); minimize weight of the door
itself, which must be shipped and installed; minimize costs (that is,
minimize capital expense); minimize thickness of the door to decrease the
footprint of the electronics rack and heat exchanger door together; and
ensure flow uniformity across the parallel flow paths through the heat
exchanger door.

[0055] To achieve the conflicting goals of maximizing heat removal, while
maintaining an acceptably low air-side pressure drop, numerous mechanical
structural changes are disclosed herein, so as to maximize the height and
width of the heat exchanger core to be as close to the height and width
of the heat exchanger door as possible. Advantageously, as the core is
made wider, a greater fin surface area is achieved, and there is a
decrease in the inlet air velocity entering the heat exchanger door, that
is, a larger frontal area for the same volumetric flow rate, and hence, a
lower air-side pressure drop is achieved. It is also possible to lower
the fin density while maintaining the same surface area, and thereby
significantly decrease the air-side pressure drop due to the effects of
lower inlet velocity and lower fin pitch. With respect to the heat
exchanger core, the following dimensions are significant: height of the
heat exchanger door; height of the exchanger core itself; unusable height
for the heat exchanger core; the width of the electronics rack, and thus
(in one embodiment) the width of the heat exchanger door; the width of
the heat exchanger core; and the unusable width of the heat exchanger
door for the heat exchanger core. Note that as used herein, the heat
exchanger core is assumed to have a width and height substantially
corresponding to an airflow opening formed within the door frame or
assembly of the heat exchanger door. Thus, maximizing the size of the
heat exchanger core corresponds, in one embodiment, to maximizing the
size of the airflow opening in the door frame.

[0056] By way of example, certain mechanical changes disclosed herein may
be made to a heat exchanger door configuration, without changing the
overall height and width of the door, which advantageously allow for an
increase in the heat exchanger core size. Significantly, an increase in
the heat exchanger core width by, for example, 52 mm increases the
surface area of the heat exchanger, and allows for a significant decrease
in fin density while maintaining the same heat removal. Due to the wider
core, the average air velocity entering the heat exchanger door also
decreases, since there is a larger frontal area for the same volumetric
flow rate to, for example, 88% (wherein pressure drop is typically
proportional to velocity squared), and the fin density is much lower,
creating much less restriction to the airflow. Coupling these effects
allows the air-side pressure drop to be decreased by, for example, 45%,
which is a dramatic reduction, achieved without changing the overall
height and width of the heat exchanger door.

[0057] As noted, disclosed herein are numerous structural modifications
and enhancements to a heat exchanger door, which are presented with the
goal of maximizing the amount of heat which can be removed from the
airstream passing through the electronics rack, while minimizing pressure
drop across the heat exchanger door. Also, the heat exchanger door
disclosed herein may be employed at either the air inlet side or the air
outlet side of the electronics rack, or both, with the discussion
presented below assuming that the heat exchanger door is mounted to the
air outlet side of an electronics rack, again by way of example only.

[0058] Note that the air-to-coolant heat exchanger disclosed herein is
advantageously designed to function without added air-moving devices
within the electronics rack or within the heat exchanger door. Therefore,
air impedance of the heat exchanger door is designed to be as low as
possible. This is achieved by controlling various design variables
discussed herein, including, for example, the number of coolant tubes,
and size of coolant tubes employed in the tube sections of the heat
exchanger, and the number, configuration, thickness, and depth in the
airflow direction of the fins used in the air-to-coolant heat exchanger.
Additionally, the air-to-coolant heat exchanger may be designed to
operate (in one embodiment) using, for example, above-dew-point coolant,
thus eliminating any chance for condensation to occur, and the need for
condensation monitoring and draining devices. The materials and wall
thicknesses may be chosen to accommodate the air impedance design. Strict
brazing processing definition and control may be employed, along with
multiple test points in the build process, for robust, controlled
component fabrication. In combination, these considerations contribute to
ensure a leak-proof, highly reliable product which meets the design
objectives.

[0059] Ease of installation may be designed into the air-to-coolant heat
exchanger and heat exchanger door disclosed herein through the use of a
minimal number of parts, and the use of quick connect couplings. For
example, after hingedly mounting the heat exchanger door to the
electronics rack, supply and return hoses may be coupled to quick connect
couplings. Start-up may be completed by initializing the supply coolant,
and attaching a bleed tool to an upper bleed valve, that is, until all
air is removed from the piping. For purposes of handling and attaching
the heat exchanger door, components are designed for reduced weight where
possible. For example, a hybrid aluminum door frame can be employed, with
steel support plates where needed for structural integrity, to create and
provide a door with a high strength-to-weight ratio. In one embodiment,
the heat exchange tube section of the air-to-coolant heat exchanger can
comprise small diameter tubes, with minimal diameter manifolds being
used, in combination with, for example, lightweight fins (such as
aluminum fins), for the heat exchange tube sections to provide the
highest possible heat removal area, with the lowest possible weight.
Safety considerations may also be taken into account throughout the
design. For ease of handling, lifting handles may be provided on, for
example, the inner side of the heat exchanger door. Further, to protect
fins from damage and to protect the operator or bystander from contacting
sharp fins, protective perforated plates may be installed across the
inner side and/or outer side of the heat exchanger door.

[0060] Generally stated, disclosed herein is an air-cooling apparatus
which includes a heat exchanger door configured to hingedly mount to one
of an air inlet side or an air outlet side of an electronics rack,
wherein air moves through the electronics rack from the air inlet side to
the air outlet side thereof. The heat exchanger door includes a door
frame sized and configured to span at least a portion of the air inlet
side or the air outlet side of the electronics rack, and an
air-to-coolant heat exchanger supported by the door frame. The door frame
includes an airflow opening which facilitates the ingress or egress of
airflow through the electronics rack with the heat exchanger door mounted
thereto, and the air-to-coolant heat exchanger is configured and disposed
so that airflow through the airflow opening passes across the
air-to-coolant heat exchanger. The air-to-coolant heat exchanger is
configured to extract heat from airflow passing thereacross.

[0061] Numerous enhancements to the air-cooling apparatus, including the
heat exchanger door, are disclosed herein, including: providing manifold
coupled, quick connect couplings within the heat exchanger door at a
right angle to vertically-extending coolant inlet and outlet manifolds;
providing a door latch mechanism and catch bracket which allows the door
latch mechanism to reside entirely within the heat exchanger door;
providing an inwardly curved or inwardly angled latch edge on the heat
exchanger door, such that the diagonal of the heat exchanger door from
the hinge axis to the latch edge is pulled in somewhat; forming the
structural door at least partially around the heat exchanger core itself
by providing, for example, a beam box or tubular door support structure
integrated with a casing of the heat exchanger core such that heat
exchanger core bends or turns reside within the tubular door support
structure; hinging the heat exchanger door at the outer side of the heat
exchanger door, away from the electronics rack to which the heat
exchanger door is mounted using, for example, upper and lower hinge
brackets, with respective hinge pins extending into the heat exchanger
door; designing the heat exchanger door to be symmetrical so that the
door can be flipped upside down using the same door latch mechanism
position and hinge pins, for example, to allow for coupling of the door
to overhead coolant supply and return headers; the use of counter-flow
circuits to maximize heat removal from the heat exchanger core, along
with numerous heat exchanger core design optimizations and a process for
maximizing heat exchanger core design. These and other aspects of the
air-cooling apparatus and heat exchanger door described herein,
collectively contribute to enlarging the size of the heat exchanger core
without changing the overall height or width of the heat exchanger door,
and thus to meeting the above-stated goals of maximizing the amount of
heat which can be removed from the airstream, while minimizing the
air-side pressure drop across the heat exchanger door.

[0062] FIGS. 5A & 5B depict one embodiment of an assembly comprising a
heat exchanger door 510 hingedly mounted at a vertically-extending hinge
edge 511 of the heat exchanger door to an electronics rack 500 at, for
example, an air outlet side of the electronics rack. Heat exchanger door
510 includes an enlarged air-to-coolant heat exchanger 520 (FIG. 5B)
having a larger height and width compared with the air-to-coolant heat
exchanger of the outlet door described above in connection with the
embodiment of FIG. 4. This is achieved without changing the overall
height or width of the door itself, but rather, by reconfiguring the
structure of the door and components within the door to accommodate a
significantly larger air-to-coolant heat exchanger 520 core footprint. In
the embodiment depicted, heat exchanger door 510 includes, in addition to
hinge edge 511, a vertically-extending latch edge 512 disposed opposite
to hinge edge 511, and an inner side 513 and an outer side 514, which are
opposite main sides of the heat exchanger door. In the embodiment
depicted, inner side 513 is disposed closer to the air outlet side or air
inlet side of electronics rack 500 with heat exchanger door 510 latched
to the electronics rack, as illustrated in FIG. 5A. Heat exchanger door
510 mounts, in one embodiment, via top and bottom hinge brackets 530 and
hinge pins 531 located at or adjacent to hinge edge 511 of heat exchanger
door 510. As illustrated, hinge pins 531 may be positioned close to outer
side 514 of heat exchanger door so that the hinge axis 515 is out from
the electronics rack to, at least in part, minimize or even eliminate the
outward swing of the heat exchanger door past electronics rack sides 501,
502, as heat exchanger door 510 is rotated between open and closed
positions. As described further below, a door latch mechanism 540 is
disposed (in one embodiment) adjacent to latch edge 512 and is configured
to facilitate latching of heat exchanger door 510 to electronics rack 500
when in the closed position (illustrated in FIG. 5A). As noted,
perforated screens may be provided at inner side 513 and/or outer side
514 of heat exchanger door 510, if desired.

[0063]FIG. 6 illustrates an inner side, isometric view of a partially
assembled heat exchanger door 510, which is shown to include
vertically-oriented, coolant inlet and outlet manifolds 600, 610 disposed
adjacent to latch edge 512 of the heat exchanger door. In addition, right
angle adapters are installed at the ends of the manifolds, with quick
connect couplings 601, 611 that facilitate ready attachment of supply and
return hoses (not shown) within the bottom of the heat exchanger door to
the connects. By way of example, industry standard, hydraulic quick
connect couplings may be employed, such as a 3/4'' quick connect female
coupling and a 3/4'' quick connect male coupling, such as Series-60
general purpose couplings, offered by Parker Hannifin Corporation, of
Minneapolis, Minn., USA. The supply and return hoses can pass through
bottom openings (not shown) adjacent to the hinge edge 511 of the heat
exchanger door, which are configured to accommodate the respective
coolant hoses. In one embodiment, the coolant supply and return hoses
would connect to coolant supply and return manifolds disposed below a
raised floor of the data center, such as described above in connection
with FIG. 3.

[0064] The heat exchanger core 520 includes a plurality of heat exchange
tube sections which couple in fluid communication to coolant inlet
manifold 600 and coolant outlet manifold 610. Each heat exchange tube
section may includes at least one of a continuous tube or multiple tubes
connected together to form, for example, a continuous serpentine cooling
channel. In the embodiment shown, each heat exchange tube section may be
a continuous tube having a first diameter, and each coolant manifold 600,
610 may be a tube having a second diameter, wherein the second diameter
is greater than the first diameter. The first and second diameters are
chosen to ensure adequate supply of coolant flow through the multiple
heat exchange tube sections. In the embodiment of FIG. 6, the thermally
conductive fins attached to the tubes are not illustrated. By way of
example, in one embodiment, the plurality of tubes (or tube sections) may
extend principally horizontally, and the plurality of thermally
conductive fins (not shown) may extend principally vertically.

[0065] One or more small air bleed lines and valves 620 may be located at
the top of the manifolds. Air bleed tools can be used to capture any
exiting coolant during start-up. Another small drain line and valve 621
may be located at a lowest point of the manifold system to facilitate
draining the heat exchanger door, if necessary. By way of example, the
air bleed valves at the ends of the air bleed lines could comprise
Schrader valves, such as those offered by JIB Industries, of Aurora,
Ill., USA.

[0066] Advantageously, by making a right angle turn from the manifolds,
before coupling to the supply and return hoses, horizontally attaching
the hoses within the heat exchanger door along the bottom of the heat
exchanger door is achieved, which allows the height of the heat exchanger
core to come closer to the height of the heat exchanger door itself. This
one change may advantageously allow the unusable height of the door for
the heat exchanger core to decrease by 50% from, for example, the
configuration depicted in FIG. 4.

[0067]FIG. 7A is a partial cross-sectional plan view of heat exchanger
door 510, and a portion of electronics rack 500, with the heat exchanger
door 510 shown in a latched position, secured by door latch mechanism 540
contacting a catch bracket 700. As illustrated, catch bracket 700 is
mounted to the electronics rack and sized to extend from the electronics
rack into heat exchanger door 510 through a catch opening (not shown) at
the inner side 513 of heat exchanger door 510. Note that, in this
embodiment, door latch mechanism 540 advantageously resides entirely
within the heat exchanger door 510, and that latching to catch bracket
700 occurs within the heat exchanger door itself by the door latch
mechanism physically engaging the catch bracket within the door, thereby
ensuring latching of the door to the electronics rack. This is contrasted
with a conventional rack door latch, which typically extends from the
door into the electronics rack in order to engage an element within the
electronics rack.

[0069] Note that in the embodiment of FIGS. 7A-7C, door latch mechanism
540 comprises a base structure 730 mounted to the door frame at or near
outer side 514 of the door, for example, so as to reside within a
symmetrical recess 740 (FIG. 7A) at latch edge 512 of the heat exchanger
door. Latching of heat exchanger door can be accomplished by closing the
heat exchanger door against the electronics rack, and actuating by an
operator latch lever 710 to move a latch surface 711 of latch lever 710
into physical engagement with a catch surface 712 of catch bracket 700.
As noted, this occurs within the heat exchanger door 510.

[0070] Note with reference to FIGS. 7A & 7B, that a U-shaped bracket 750
may be employed in mounting base structure 730 of door latch mechanism
540 to a wall of the door frame. In one embodiment, U-shaped bracket 750
may be secured in bracket-receiving channels via an appropriately-sized
bolt 751.

[0071] FIGS. 8A & 8B depict front and back isometric views of one
embodiment of a door latch mechanism, such as described above in
connection with FIGS. 7A-7C. In one implementation, door latch mechanism
540 may comprise a lever-type latch, such as offered by Southco, of
Concordville, Pa., USA.

[0072]FIG. 9 illustrates an isometric view of catch bracket 700 depicted
in FIGS. 7A-7C. In one embodiment, catch bracket 700 is fabricated of a
one-piece construction, for example, from a rigid material, such as a
metal plate. Catch bracket 700 has a length "l" sufficient for catch
surface 712 to reside within the heat exchanger door and be positioned
for the pivoting latch lever 710, and in particular, latch surface 711
thereof, to engage the catch surface 712 when the latch lever is in the
latched position (illustrated, by way of example, in FIGS. 7A & 7B).
Catch bracket 700 has a rack-mount portion 900 with, for example,
attachment openings 910 which allow for bolting of the rack-mount portion
900, and thus the catch bracket 700, to a corresponding plate (or flange)
within the electronics rack, such as illustrated in FIG. 7A. Depending on
the orientation of this plate, the angling of the rack-mount portion 900
may change. Note that, in one embodiment, catch surface 712 is oriented
substantially parallel to the inner side 513 of heat exchanger door 510,
and is thus substantially parallel to the air inlet side and air outlet
side of the electronics rack when the heat exchanger door is in latched
position.

[0073] Advantageously, by providing a catch bracket which extends into the
heat exchanger door, and by configuring, sizing and placing the door
latch mechanism entirely within the heat exchanger door, the latch
mechanism can move towards the latch edge of the heat exchanger door,
thereby achieving a goal of expanding the heat exchanger core width. Note
that this additional space is achieved by the placement of the door latch
mechanism within the door frame and, for example, by configuring the
attachment bracket as a U-shaped bracket to closely wrap around the base
structure of the door latch mechanism. Also, note that the door latch
mechanism disclosed herein is decoupled from the rack flange width. This
is significant for both maximizing core width, and adding design
flexibility for multiple electronics rack configurations. In the
embodiment depicted in FIGS. 7A-7C, the door latch mechanism is not a
gate to the heat exchanger core width. In one embodiment, this enables a
greater core width, and with an even skinnier latch configuration, would
allow for further expansion of the heat exchanger core width. In
particular, the door latch mechanism configuration and placement
disclosed herein means that the latch itself does not have to cross the
plane of the electronics rack, which has certain key advantages, and in
particular: the heat exchanger core width can be insensitive to the
electronics rack design, by just defining different door catch brackets;
and the heat exchanger core width can be maximized, since it is not
limited by the electronics rack geometry.

[0074] As a further advantage, by providing the catch bracket to extend
into the heat exchanger door, and by configuring, sizing and placing the
door latch mechanism entirely within the heat exchanger door, the latch
mechanism is isolated from any wiring or cabling within the electronics
rack that might otherwise be inadvertently engaged by the latch
mechanism, and does not constrain cabling space within the electronics
rack.

[0075] Referring to FIG. 10, as noted above, in another aspect, the hinge
axis 515 of heat exchanger door 510 is disposed (in one embodiment) at an
outer corner of the heat exchanger door, at the door corner between hinge
edge 511 and outer side 514. Hinge brackets 530 (FIG. 5A) may be mounted
above and below the electronics rack 500 to facilitate this hinge axis
location. This allows for the heat exchanger door to be opened adjacent
to, for example, another assembly comprising an electronics rack with a
similar heat exchanger door or, for example, for the door to be opened
adjacent to a wall of the data center. Advantageously, by moving the door
latch mechanism 540 to reside entirely within the heat exchanger door as
described herein, additional space is freed at the diagonally-opposite
corner of the heat exchanger door 510, that is, at the corner defined by
latch edge 512 and the inner side 513 of the heat exchanger door. This
allows for the latch edge 512 to either curve inward or angle inward
from, for example, outer side 514 towards inner side 513, as illustrated
(by way of example) in the cross-sectional plan view of FIG. 10. This
advantageously results in a pulling in of the diagonal distance along
diagonal line 1000 to that of diagonal line 1001, to gain core width from
the refrigerator hinge point.

[0076] As a further design advantage, the heat exchanger door described
herein with reference to FIGS. 5A-10 may be configured so that the door
can be installed upside down to, for example, move the hinge edge from
one side of the electronics rack to the other side. This ability to flip
the heat exchanger door upside down is achieved using the same door latch
mechanism in the same vertical location in the heat exchanger rack. If
flipped upside down, the air bleed and drain bleed lines would reverse
function, with extra care being taken to bleed air from the heat
exchanger core in the upside down version. Note that an extra set of
hinge plates might be needed in order to flip the heat exchanger door
upside down in order to mount the door to a different side of the
electronics rack. Mounting the heat exchanger door upside down as
described herein would advantageously place the quick connects for the
coolant inlet and outlet manifolds at the top of the heat exchanger door,
and thus facilitate coupling of the heat exchanger door to overhead
coolant supply and return manifolds, depending upon the configuration of
the data center.

[0077] As another enhancement, disclosed herein is an enhanced structural
configuration of a heat exchanger door comprising a door assembly sized
and configured to span at least a portion of the air inlet side or the
air outlet side of the electronics rack. The door assembly includes an
airflow opening which facilitates the ingress or egress of airflow
through the electronics rack with the heat exchanger door coupled
thereto. Further, the door assembly includes an air-to-coolant heat
exchanger and a structural support. The air-to-coolant heat exchanger is
disposed so that airflow through the airflow opening passes across the
air-to-coolant heat exchanger, and is configured to extract heat from the
airflow passing thereacross. The heat exchanger includes a heat exchanger
core and a heat exchanger casing coupled to the heat exchanger core. The
heat exchanger core includes at least one coolant-carrying channel which
loops through the heat exchanger casing at one side or edge of the heat
exchanger core. The structural support is attached to the heat exchanger
casing, and together the structural support and the heat exchanger casing
define a tubular door support beam or structure, wherein the at least one
coolant-carrying channel loops through the heat exchanger casing within
the tubular door support beam.

[0078] Advantageously, the above-described integrating or forming of the
tubular door support beam or structure about the heat exchanger casing
compacts the door frame, and thus allows a further increase in the heat
exchanger core width for a given overall heat exchanger door size. In one
embodiment, the heat exchanger casing defines, at least partially, one or
more sides of the tubular door support beam, and results in a stiff,
strong, lightweight support structure, which, in one embodiment, is
provided in an almost direct path with a hinge axis of the heat exchanger
door. In such an embodiment, the hinge loading is advantageously
transitioned into the heat exchanger with which the tubular door support
beam is integrated, and not through a separate door frame surrounding the
heat exchanger.

[0079] Referring collectively to FIGS. 11A-11C, one embodiment of a heat
exchanger door 510 is depicted which comprises a door assembly 1100. Door
assembly 1100 includes an outer door shell (or wrap) 1105 with an airflow
opening 1101 configured to facilitate the ingress or egress of airflow
through an electronics rack with the heat exchanger door coupled thereto.
In one embodiment, door shell 1105 may comprise a single-piece, outer
wrap or shell, which provides additional structure to the heat exchanger
door, without consuming any significant core width, and adds minimal
weight to the heat exchanger door.

[0080] As illustrated, the door assembly includes air-to-coolant heat
exchanger 520, such as described above in connection with FIGS. 5A-10. In
one embodiment, air-to-coolant heat exchanger 520 includes one or more
coolant-carrying channels defined by one or more tubes in one or more
tube sections. In one implementation, the one or more tubes transverse
one or more times across the width of the heat exchanger core and back,
after making a 180° turn or loop. Also as noted above, each heat
exchange tube section may be a continuous tube having a first diameter,
and that couples to the coolant inlet and outlet manifolds 600, 610, each
of which may be a tube having a second diameter, wherein the second
diameter is greater than the first diameter. As noted above, the first
and second diameters are chosen to ensure adequate supply of coolant flow
through the multiple heat exchange tube sections. The tube sections have
a plurality of thermally conductive fins 1111 coupled thereto (only one
of which is illustrated), which together define a heat exchanger core
1110 of the air-to-coolant heat exchanger 520. As illustrated in FIGS.
11A-11C, heat exchanger core 1110 is surrounded, in one example, by a
heat exchanger casing 1120. In one embodiment, heat exchanger casing 1120
provides structural support for heat exchanger core 1110.

[0081] In accordance with an aspect of the present invention, a structural
support (or channel plate) 1130 is attached to heat exchanger casing
1120, for example, along a vertically-extending edge of the heat
exchanger core. Optionally, an upper hinge support bracket 1135 and a
lower hinge support bracket 1136 may also be employed to provide
additional structural rigidity to the tubular door support beam defined
by structural support 1130 attached to heat exchanger casing 1120.
Multiple fasteners, such as bolts, screws, rivets, etc., may be employed
in securely, rigidly attaching structural support 1130, upper and lower
hinge support brackets 1135, 1136, and heat exchanger casing 1120
together, and thus define the tubular door support beam such as disclosed
herein. In the embodiment illustrated, the heat exchanger door also
comprises a perforated inner screen 1140 and a perforated outer screen
1141, which can be employed (for example) to prevent an operator from
physically contacting any sharp edges within the door assembly 1100, and
to protect the heat exchanger fins from damage.

[0082] FIGS. 11B & 11C depict enlarged views of the upper and lower
portions of the partially exploded door assembly 1100 of FIG. 11A. In the
embodiment illustrated, heat exchanger casing 1120 wraps around heat
exchanger core 1110, and includes opposite, vertically-extending casing
portions 1121, 1122, and opposite, horizontally-extending casing portions
1123, 1124. The tubular support beam disclosed herein is formed, in one
embodiment, around vertically-extending casing portion 1121, disposed
opposite to vertically-extending heat exchanger casing 1122, adjacent to
which (in one embodiment) the coolant inlet and outlet manifolds 600, 610
are disposed (see FIGS. 6 & 10). Heat exchanger casing portion 1121
comprises, by way of example, a first plate 1125 with flanges 1126
extending therefrom. Similarly, structural support 1130 comprises, in one
embodiment, a second plate 1131 with flanges 1132 extending therefrom. As
shown, second plate 1131 with flanges 1132 is sized and configured to
physically contact first plate 1125 with flanges 1126. When assembled and
attached as depicted, a tubular door support beam or structure is
defined, which in one embodiment, is an elongate, tubular beam integrated
with the heat exchanger and oriented substantially vertically within the
door assembly. This resultant tubular door support beam is, in one
embodiment, rectangular-shaped in transverse cross-section.

[0083] By way of specific example, heat exchanger casing 1120 and support
structure 1130 may each be fabricated of aluminum, in which case, upper
hinge support bracket 1135 and lower hinge support bracket 1136, may be
fabricated of a more structurally rigid material, such as steel. Note
that in an alternate embodiment, support structure 1130 may be
fabricated, for example, of steel, in which case, upper and lower hinge
support brackets 1135, 1136 could be omitted from the door assembly, that
is, with a configuring of the top and bottom edges of the support
structure 1130 to accommodate, for example, the above-discussed hinge
pins disposed at the hinge axis. Note also that a plurality of fasteners
may be advantageously employed to distribute the load from the hinge axis
due, for example, to opening or closing of the heat exchanger door. In
addition, note that in this embodiment, the hinge axis substantially
aligns with or is within the tubular door support beam defined by support
structure 1130 and heat exchanger casing 1120, or more particularly,
vertically-extending casing portion 1121 of heat exchanger casing 1120.

[0084] As illustrated herein, the tubular door support beam is
advantageously formed around multiple coolant-carrying channel or tube
bends, which comprise loops through heat exchanger casing 1120 at
vertically-extending casing portion 1121. Advantageously, by disposing
these coolant-carrying channel or tube bends within the tubular door
support structure defined by structural support 1130 and heat exchanger
casing 1120, further compacting of the door structure is achieved. This
integrated structure is depicted in further detail in FIGS. 12A-13.

[0085] Referring to FIGS. 12A & 12B, heat exchanger door 510 is depicted
hingedly mounted along hinge axis 515 to electronics rack 500. As
illustrated, and as described above, hinge axis 515 is disposed at or
adjacent to a hinge edge 511, which in one embodiment, comprises a
vertically-extending edge or region of heat exchanger door 510 disposed
opposite to vertically-extending latch edge 512. As illustrated in FIG.
12B, coolant inlet manifold 600 and coolant outlet manifold 610 are
disposed at one side of the air-to-coolant heat exchanger 520, and the
tubular door support beam 1200 is disposed at the opposite side of the
air-to-coolant heat exchanger 520. As described above, tubular door
support beam 1200 is integrated with the air-to-coolant heat exchanger by
configuring and attaching structural support 1130 to, for example, a
vertically-extending casing portion of heat exchanger casing 1120. Note
that, as illustrated in FIG. 12B, hinge axis 515 of the heat exchanger
door 510 advantageously resides within or is aligned over the tubular
door support beam 1200 so that any load resulting from hinged opening or
closing of the heat exchanger door is distributed by the tubular door
support beam to the air-to-coolant heat exchanger 520, with which the
beam is integrated.

[0086]FIG. 13 depicts the integration of tubular door support beam 1200
with air-to-coolant heat exchanger 520 in greater detail. As illustrated,
multiple fasteners, such as rivets 1300, may be employed to couple
support structure 1130 to the heat exchanger casing 1120 at, for example,
the vertically-extending casing portion along the side of the
air-to-coolant heat exchanger. Multiple coolant-carrying channels (or
tubes) of the heat exchanger core are shown to loop 1310 through heat
exchanger casing 1120 and reside within the tubular door support beam or
structure 1200 defined by the structural support 1130 and heat exchanger
casing 1120. Also, illustrated in FIG. 13 is lower hinge support bracket
1136, which may be employed, in one embodiment, where the support
structure 1130 is fabricated of a lighter weight material, such as
aluminum.

[0087] Advantageously, integration of a tubular door support beam with the
air-to-coolant heat exchanger, and in particular, with the heat exchanger
casing, allows for a reduction in the non-usable width of the heat
exchanger door for the core, and thus allows for the heat exchanger core
to be expanded. In essence, the heat exchanger itself becomes at least
partially the structure of the door, with any hinge loading going
directly to the heat exchanger, and not through, for example, a
structural door frame encircling the heat exchanger. An outer shell (or
wrap) may be provided to add some additional structural support, without
consuming any significant core width, and adding minimal weight. The
above-described integration of the tubular door support beam with the
heat exchanger advantageously allows for the heat exchanger door to be
shipped mounted to the electronics rack, which requires a robust
construction. This is achieved, as explained above, without consuming the
critical width of the heat exchanger core.

[0088] By integrating the tubular beam with the heat exchanger core such
that the loops or bends of the tubes at least partially reside within the
tubular beam, a more compact structure is obtained. The entire
construction may be secured together via, for example, riveting,
resulting in a strong and stiff construction, low cost, lightweight heat
exchanger door and tubular beam. Upper and lower hinge support brackets
may optionally be provided to distribute any load, for example, from
shock or vibration, to the tubular beam. The resultant structure is very
space efficient, and allows a maximization of heat exchanger core width.
In one embodiment, by integrating the tubular beam with the heat
exchanger core as described herein, approximately 10-25 mm of additional
heat exchanger core width can be obtained.

[0089] In accordance with further aspects of the present invention, and as
described above, the air-to-coolant heat exchanger disclosed herein
includes one or more coolant-carrying channels, such as channels defined
by one or more tubes arranged in one or more tube sections. In one
embodiment, each heat exchange tube section may comprise a continuous
tube having a first diameter which couples to the coolant inlet and
outlet manifolds. The inlet and outlet manifolds may each be a tube
having a second diameter, wherein the second diameter is greater than the
first diameter. The first and second diameters are chosen to ensure
adequate supply of coolant flow through the multiple heat exchange tube
sections. In another embodiment, the cross-sectional area in the
direction of the coolant flow path may vary and be tailored to ensure
that coolant uniformly flows through the plurality of coolant channels
(also referred to herein as a plurality of coolant circuits).

[0090] The coolant inlet and outlet manifolds may be manufactured from any
desired material or combination of materials. Factors such as material
properties, cost, manufacturing considerations, and other characteristics
may be taken into consideration when determining the material or
materials of the coolant inlet and outlet manifolds. In one embodiment,
the coolant inlet and outlet manifolds may be copper tubes.

[0091] As discussed above, the coolant channels may have one or more fins
coupled thereto, which together define the heat exchanger core of the
air-to-coolant heat exchanger. These fins act to increase heat transfer
to the coolant in the channels by increasing the surface area of the heat
exchanger core in contact with the airflow thereacross, and are coupled
to, or otherwise in contact with, the one or more coolant channels so
that heat is transferred from the airflow to the coolant. The fins may
take various forms or shapes, such as a helical fin or a plate fin. For
example, the fins may be any plate fin, such as a flat plate fin, a sine
wave fin, a corrugated fin, a louvered fin, etc., or combinations
thereof. Depending on the implementation, the finstock thickness between
heat exchangers may vary. For example, the finstock thickness may be
within a range of about 0.0035 to 0.0095 inches thick.

[0092] Similar to the manifolds, the fins may be manufactured from various
materials or combination of materials by various methods. Factors such as
material properties, cost, manufacturing concerns and other
characteristics may be taken into consideration when determining the fin
material or materials.

[0093] In one embodiment, the heat exchanger core may include a plurality
of fins spaced substantially across the width of the heat exchanger core.
In such an embodiment, the plurality of fins may be spaced from one
another with a regular fin pitch or density, and configured so that air
readily passes between adjacent fins. By way of example, the fin pitch
may be between about 5 fins per inch to about 20 fins per inch.

[0094] The size, shape, orientation, pitch (e.g., fins/inch), material
properties, surface finish and/or texture and other aspects of fin
construction may contribute to heat removal capability and to air
pressure drop across the air-to-coolant heat exchanger. These fin
attributes may be selected in combination with other aspects of the heat
exchanger core, such that the air pressure drop and heat removal of the
air-to-coolant heat exchanger are both optimized, that is, for one or
more boundary conditions. Note that as used herein, "optimized" heat
exchanger metrics refers to a best or desirable combination of metrics
for a particular application, and may include, for example, a maximum
heat removal capability with a minimum air pressure drop across the heat
exchanger. The fins may also contribute to other characteristics or
metrics of the air-to-coolant heat exchanger, and/or the heat exchanger
core, such as weight, cost, depth and height of the heat exchanger. As
such, aspects of the fins may also be optimized in consideration of such
other characteristics or metrics. For example, the fins may be optimized
for one or more boundary conditions, for air pressure drop, heat removal,
weight, depth, cost and/or combinations thereof.

[0095] As described above, the heat exchanger core of the air-to-coolant
heat exchanger includes a plurality of channels or tubes for the flow of
coolant therethrough. By way of example, channel inlets may be coupled in
fluid communication with the coolant inlet manifold, and channel outlets
may be coupled in fluid communication with the outlet manifold. This
allows coolant to flow through the inlet manifold, into the plurality of
coolant channels via their corresponding channel inlets, through the
plurality of coolant channels, and from the coolant channels and into the
coolant outlet manifold via their corresponding channel outlets. In
certain embodiments, the inlet and outlet of a coolant channel may be
considered to be the openings in the inlet and outlet manifolds, which
allow coolant to flow to or from the coolant channels.

[0096] The coolant channels themselves may be defined by a variety of
structures. For example, a coolant channel may be formed from a
continuous structure, or from multiple structures connected together.
Further, the structure defining the coolant channel may be made from a
variety of materials or combination of materials. Factors such as
material properties, cost, manufacturing concerns and other
characteristics may be taken into consideration when determining a
material for the coolant channels. In one embodiment, the plurality of
coolant channels include or are defined by copper tubing.

[0097] As another consideration, the cross-sectional area of a coolant
channel in the direction of the coolant flow path may be constant or may
vary. Further, the shape of a coolant channel (interior and/or exterior)
may be constant or may vary, and may be any desired cross-sectional
shape. In some embodiments, each coolant channel of the plurality of
coolant channels has a substantially similar shape and size, and each
coolant channel is defined by substantially similar, but distinct,
structures. In other embodiments, two or more coolant channels of the
plurality of coolant channels may have a substantially dissimilar shape
and/or size. In some embodiments, two or more of the coolant channels may
be identically formed. In certain embodiments discussed herein, the
plurality of coolant channels are defined by one or more tube structures,
and the cross-sectional area of the coolant channels in the direction of
coolant flow path is substantially constant. In one embodiment, the tubes
defining the coolant channels may be fabricated of commercially available
tubing.

[0098] As described above, the plurality of coolant channels may extend
substantially across the airflow to be cooled, such as back-and-forth
across the airflow opening of the heat exchanger door. The total number
of tubes (or other shaped structures) of a particular heat exchanger
core, may depend upon the size and/or shape of the tubes (i.e., the
structure defining the coolant channels), the available heat exchanger
core depth and height, the number of rows of the tubes in the direction
of the airflow, the tube spacing in the vertical and horizontal
directions, the arrangement of the tubes, the positioning and/or
orientation of the tubes, and the like. In certain heat exchanger core
embodiments, the portions of the plurality of coolant channels extending
across the airflow (and/or an airflow opening) are substantially arranged
in horizontal rows in the direction of airflow. For example, the portions
of the channels extending across the airflow may be substantially
arranged in two, three, or four (or more) rows, such as illustrated in
FIGS. 14-16 and discussed below. In certain embodiments, the vertical
spacing between the portions of the channels extending across the airflow
may be greater than the spacing in the direction of the airflow (i.e.,
the spacing between rows).

[0099] In embodiments wherein the plurality of coolant channels are
defined by substantially identical tubes, and the tubes extend
substantially horizontally across the airflow (or airflow opening), the
diameter of the tubes, the spacing in the vertical and horizontal (or
airflow) directions, the heat exchanger core height and the number of
rows of the tubes in the direction of the airflow together effect the
total number of tubes in a particular heat exchanger core design. Note
that in other embodiments, the structure defining the plurality of
coolant channels need not extend substantially horizontally across the
airflow opening. Similarly, in certain embodiments, the portions of the
channels extending substantially across the airflow need not be aligned
and, thus, need not extend parallel to each other.

[0100] As discussed above with respect to the fins, the parameters,
aspects or characteristics of the coolant channels may affect the
performance metrics of the heat exchanger. For example, the size and
shape of the structure (or structures) defining the coolant channels, the
number of rows of cooling channels, the channel or tube spacing in the
vertical and the airflow directions, the total number of coolant channels
extending across the airflow, the number of coolant channels or circuits
(e.g., the number of discrete pathways of coolant from the inlet manifold
to the outlet manifold) may affect the heat removal of the heat
exchanger, the air side pressure drop, the water side pressure drop, the
core weight, the core depth and/or the cost of the heat exchanger. As a
result, in certain embodiments, at least one variable parameter of the
coolant channels, such as one of the parameters listed above, may be
chosen to optimize one or more performance metrics of the heat exchanger
core in which the plurality of coolant channels are installed for
particular boundary conditions. For example, in a heat exchanger
embodiment where tubes define the plurality of coolant channels, a
combination of two or more of tube diameter, the number of rows of the
tubes in the airflow direction, tube spacing in the vertical and/or
horizontal directions, core height, number of coolant channels or coolant
circuits and non-variable parameters of the heat exchanger may affect
optimization of the air pressure drop, heat removal, weight, depth and
cost of the heat exchanger for particular boundary conditions.

[0101] As noted, the number of coolant channels may vary (i.e., may be a
variable parameter of the heat exchanger), and may affect one or more
performance metrics of the heat exchanger in which the coolant channels
are installed. For example, the number of coolant channels (i.e., the
number of discrete flow paths for the coolant) may affect the heat
removal, water side pressure drop, core weight, coolant flow
distribution, cost, etc.

[0102] FIGS. 14-16 illustrate several coolant channel configurations for
consideration of certain of the parameters described above. By way of
example, FIG. 14 is a side illustration of a portion of a plurality of
cooling channels (or circuits) 1400 with an airflow 1401 passing across
the plurality of cooling channels 1400 traveling (by way of example only)
substantially left-to-right (as indicated by the arrow). As shown, the
plurality of cooling channels 1400 are defined by tubes that extend (in
one embodiment) substantially linearly horizontally, and therefore
parallel to one another, across airflow 1401. The linear tubes or
portions that extend across airflow 1401 are arranged (in this example)
in two rows in the direction of the airflow 1401, and are illustrated in
FIG. 14 as circles 1410 (i.e., as tubes extending along a direction
extending into, or out of, the page). Note that as used herein, "row" is
used to refer, for example, to a two-row heat exchanger, three-row heat
exchanger, four-row heat exchanger, etc., when viewed in top plan view.
In side elevational view, a "row" as used herein appears as a column of
coolant-carrying channels or tubes (such as depicted in FIGS. 14-16).
Note also, the heat exchanger examples presented herein are configured in
a counter-flow arrangement with, for example, airflow 1401 moving
left-to-right across the heat exchanger and coolant moving through the
cooling channels (or circuits), generally from right-to-left within the
heat exchanger between a channel inlet and a channel outlet. that is, for
many of the cooling channels within the heat exchanger. This counter-flow
arrangement is also illustrated in FIGS. 14-16, and discussed further
below.

[0103] Each of the plurality of cooling channels 1400 of FIG. 14 extends
from an inlet manifold 1402 that supplies coolant to the cooling channels
1400, to an outlet manifold 1404 that provides an outlet for the coolant
after flowing through the cooling channels 1400. The flow path of the
coolant is indicated in the inlet and outlet manifolds 1402, 1404 by
arrows. Each of the cooling channels 1400 includes a channel inlet 1406
and a channel outlet 1408. In the illustrated embodiment, the inlets 1406
may extend from the inlet manifold 1402 to a first tube portion 1410A
(solid circle) that extends across the airflow 1401. The first tube
portion 1410A is a first tube portion of each of the cooling channels
1400 in the direction of the coolant flow path. Similarly, the outlets
1408 may extend from the outlet manifold 1404 to the last tube portion
1410B (solid circle) that extends across the airflow 1401. This last tube
portion 1410B is the last channel portion of each of the cooling channels
1400 in the direction of coolant flow.

[0104] After first tube portion 1410A of each of cooling channel 1400
extends across the airflow 1401, the cooling channel loops, bends or
otherwise changes direction such that the channel extends back across the
airflow 1401 for a second pass (outlined circle) across the airflow 1401,
as shown. The loop or bend 1412 that acts to redirect the channel back
across the airflow 1401 on the opposing side of the heat exchanger, is
represented or indicated by a single straight line in FIG. 14. Once back
on the "inlet side" of the airflow 1401, the channel (and therefore
coolant carried therein) is again redirected such that it extends back
for a third pass (outlined circle) across the airflow 1401. The loop 1414
that acts to redirect the channel or tube back across the airflow 1401
from the "inlet side" of the airflow 1401 is indicated by a double line
in FIG. 14. In such a manner, the cooling channels 1400, and the coolant
carried therein, zigzag, crisscross, or otherwise travel back and forth
across the airflow 1401 (or an airflow opening). Adjacent portions of the
cooling channels 1400 in the direction of the coolant flow that extend
across the airflow 1401 are thus configured in an alternating flow
arrangement.

[0105] As discussed above, in one embodiment, the coolant channels extend
back and forth across the airflow 1401 until last tube portion 1410B
(solid circle) that is coupled to the outlet 1408 and the outlet manifold
1404. Thereby, the flow path of the coolant through the coolant channels
1400 and the inlet and outlet manifolds 1402, 1404, can be said to extend
from a first fixed point 1420 in the inlet manifold 1402, through the
inlets 1406 and into the coolant channels 1400, through the portions of
the cooling channels 1400 extending across the airflow 1401 and the loops
1412, 1414 therebetween, through the outlets 1408 and into the outlet
manifold 1404, and finally through the outlet manifold 1404 to a second
fixed point 1422 in the outlet manifold 1402.

[0106] In the embodiment depicted in FIG. 14, the coolant channels 1400
include discrete channels that differ from one another. For example, some
of the channels include differing positioning and patterns of tube
portions 1410 that extend across the airflow 1401. Stated differently,
the pattern of the vertical and horizontal spacing between adjacent
portions 1410 of the channels in the direction of the coolant flow path
may differ between coolant channels. Still further, the total length of
the coolant channels 1400 may differ from one another.

[0107] By way of specific example, the first coolant channel 1400A of the
plurality of coolant channels 1400 fed by the inlet manifold 1402 may
include four consecutive channel portions 1410 in a first row (including
the first portion 1410A (solid circle)), followed by ten channel portions
1410 that alternate between the second and first rows, and finally four
consecutive channel portions 1410 in the second row (including the last
portion 1410B (solid circle) that is adjacent to the outlet 1408). The
coolant channel 1400A therefore includes sixteen portions 1410 that
extend substantially across the airflow 1401 (including the first and
last portions or tubes 1410A, 1410B). In contrast, the second coolant
channel 1400B fed by the inlet manifold 1402 (i.e., in the direction of
the coolant flow) includes four consecutive channel portions 1410 in a
first row (including the first portion 1410A (solid circle)), followed by
four channel portions 1410 that alternate between the second and the
first rows, and finally four consecutive channel portions 1410 in the
second row (including the last portion 1410B (solid circle)) adjacent to
the outlet 1408). The second coolant channel 1400B therefore includes
twelve portions 1410 that extend substantially across the airflow 1401
(including the first and last portions 1410A, 1410B). Thus, not only does
the pattern of the channel portions 1410 that extend across the airflow
1401 differ, the number of channel portions 1410 extending across the
airflow 1401 differ between the first and second coolant channels 1400A,
1400B.

[0108] In particular, the length of the flow path of the coolant from the
inlet 1406 to the outlet 1408 of the first coolant channel 1400A is
longer than that of the second coolant channel 1400B. Similar to the
first and second coolant channels 1400A, 1400B, the last coolant channel
(or circuit) 1400Z fed by the coolant inlet manifold 1402 includes a
different pattern of channel portions 1410 that extend across the airflow
1401, and has (by way of example) two less channel portions 1410 than a
second to last coolant channel 1400Y fed by the coolant inlet manifold
1402.

[0109] Advantageously, by decreasing the length of the coolant channels
with progression up the heat exchanger core, that is, up the manifolds,
or more particularly, where the channels couple to the coolant inlet and
outlet manifolds, a more uniform coolant flow through the heat exchanger
is achieved. By way of specific example, first coolant channel 1400A
might comprise 16 passes per circuit, second coolant channel 1400B might
comprise 14 passes per circuit, as might the second to last coolant
channel 1400Y, and the last coolant channel might comprise 12 passes. In
alternate embodiments, two or more of the first cooling channels (or
circuits) might comprise 16 passes, and two or more of the last cooling
channels might comprise 12 passes. Additionally, note with respect to the
heat exchanger embodiments described herein, that there is advantageously
counter-flow cooling. That is, assuming that airflow 1401 passes
left-to-right across the heat exchanger, from a first side to a second
side of the heat exchanger, then multiple coolant channels of the
plurality of coolant channels are configured to direct coolant from a
channel inlet disposed closer to the second side of the heat exchanger to
a channel outlet disposed closer to the first side of the heat exchanger,
and thereby provide the counter-flow cooling of the airflow. More
particularly, the airflow generally moves left-to-right in this example,
and the coolant generally moves (in addition to upwards) right-to-left.
Note that this particular counter-flow arrangement of FIGS. 14-16 is
presented by way of example only. Further, those skilled in the art will
note that the embodiments of FIGS. 15 & 16 generally have better
counter-flow cooling than the embodiment of FIG. 14.

[0110] As illustrated by the break between the upper and lower halves of
FIG. 14, second coolant channel 1400B fed by inlet manifold 1402 and the
second to last coolant channel 1400Y fed by the inlet manifold 1402, the
plurality of coolant channels 1400 may include any number, configuration
or length of channels therebetween. For example, the second coolant
channel 1400B may be repeated, which as depicted, is identical to the
second to last coolant channel 1400Y. As another example, other coolant
channels of differing lengths, arrangements, combinations or patterns may
be positioned between coolant channel 1400B and coolant channel 1400Y. In
one embodiment, the channels or circuits positioned between the coolant
channels 1400B, 1400Y in the direction of the coolant flow path may be
configured such that a majority of the first channel portions 1410A of
the plurality of coolant channels 1400 fed by the inlet manifold 1402 are
positioned in the same column. For example, most, if not all of the first
channel portions 1410A fed by the inlet manifold 1402 may be positioned
in the same column.

[0111]FIG. 15 is a side elevational view of a portion of a plurality of
cooling channels 1500 with an airflow 1501 passing thereacross, traveling
(by way of example only) substantially left-to-right (as indicated by the
arrow). The plurality of cooling channels 1500 are substantially similar
to the plurality of cooling channels 1400 described above with respect to
FIG. 14, and therefore like reference numerals preceded by "15", as
opposed to "14" are used to indicate like elements. One of the
differences between the plurality of cooling channels 1500 and the
plurality of cooling channels 1400 (FIG. 14) is the number of rows
transverse to the direction of the airflow 1501 that channel portions
1510 passing across airflow 1501 are arranged. As shown in FIG. 15, the
plurality of cooling channels 1500 include three rows of tube portions
1510 extending perpendicular (by way of example only) to the airflow
1501.

[0112] Another difference between the plurality of cooling channels 1500
and the plurality of cooling channels 1400 (FIG. 14) is the difference in
lengths of first coolant channel 1500A and second coolant channel 1500B.
As shown in FIG. 15, the first coolant channel 1500A includes two more
channel portions 1510 that extend across the airflow 1501 compared with
the second coolant channel 1500B. Therefore, the length of the coolant
flow path from the inlet 1506 to the outlet 1508 of the first coolant
channel 1500A is longer than that of the second coolant channel 1500B.

[0113]FIG. 16 is a side elevational view of a portion of a plurality of
cooling channels 1600 with an airflow 1601 passing across the plurality
of cooling channels 1600 traveling (by way of example only) substantially
left-to-right (as indicated by the arrow). The plurality of cooling
channels 1600 are substantially similar to the plurality of cooling
channels 1400 described above with respect to FIG. 14 and the plurality
of cooling channels 1500 described above with respect to FIG. 15, and
therefore like reference numerals preceded by "16", as opposed to "15" or
"14", are used to indicate like aspects. One of the differences between
the plurality of cooling channels 1600 and the plurality of cooling
channels 1500 (FIG. 15) or 1400 (FIG. 14) is the number of rows
transverse to the direction of airflow 1601 that the tube portions 1610
that pass across the airflow 1601 are arranged. In the embodiment of FIG.
16, the plurality of cooling channels 1600 include four rows of tube
portions 1610 (i.e., when viewed in top plan view).

[0114] Another difference between the heat exchanger embodiments of FIGS.
14-16 is the length of the first coolant channel 1600A and the second
coolant channel 1600B. As shown in FIG. 16, the first coolant channel
1600A includes four additional tube portions 1610 that extend across the
airflow 1601 compared with the second coolant channel 1600B. Therefore,
the length of the flow path of the coolant from inlet 1606 to outlet 1608
of the first coolant channel 1600A is longer than that of the second
coolant channel 1600B.

[0115] As noted above, the heat exchanger door, air-to-coolant heat
exchanger, heat exchanger core and the like may be optimized for one or
more metrics, such as one or more performance metrics. Numerous
parameters, aspects or characteristics of the heat exchanger door,
air-to-coolant heat exchanger and/or heat exchanger core play a role in
the metrics thereof (performance or otherwise). Further, these numerous
parameters may affect metrics differently at different operating
conditions. As such, a method for determining parameters of a heat
exchanger that optimize particular metrics of the heat exchanger at
particular operating conditions is believed valuable, and is disclosed
hereinbelow.

[0116]FIG. 17 depicts one such method 1700 for determining parameters of
a heat exchanger that optimizes one or more metrics of the heat exchanger
for particular boundary or operating conditions.

[0117] As illustrated in FIG. 17, an initial step in the process includes
obtaining non-variable parameters 1702 of the heat exchanger. This step
may include recording, selecting, identifying, inputting or otherwise
establishing the non-variable parameters of the to-be-optimized heat
exchanger. For example, if the heat exchanger is an air-to-coolant heat
exchanger, such as described herein, then the non-variable parameters may
be parameters that are fixed, difficult to alter or are otherwise held
constant. In one embodiment, one or more non-variable parameters of the
heat exchanger may be one or more of the heat exchanger core width, heat
exchanger core height, the material or materials (e.g., material
properties) of the inlet and/or outlet manifolds of the heat exchanger,
the material comprising the structures that define the coolant channels
of the heat exchanger, and the material that defines the fins of the heat
exchanger. In certain embodiments, a non-variable parameter may comprise
numerical or other discrete, manipulatable data corresponding to a
parameter (such as the numerical material properties of copper (e.g., the
density of copper, the thermal coefficient of copper, the cost of copper,
etc.)).

[0118] Another initial step includes obtaining variable parameters 1704 of
the heat exchanger. This obtaining variable parameters 1704 of the
"to-be-optimized" heat exchanger may include recording, selecting,
identifying, inputting or otherwise establishing one or more variable
parameters of the heat exchanger. For example, if the heat exchanger is
an air-to-coolant heat exchanger, then the variable parameters may be
parameters that are customizable, optional, relatively easy to alter or
are otherwise selectively held or believed to be flexible or unfixed. In
one embodiment, the one or more variable parameter of a heat exchanger
may comprise one or more of the inlet and/or outlet manifold
cross-sectional dimensions or area (inner and/or outer) in the direction
of the coolant flow, the outer and/or inner cross-sectional dimensions of
the coolant channels in the direction of coolant flow, the number of
columns of coolant channels in the transverse direction of airflow, the
depth of the heat exchanger in the direction of airflow, the type of
finstock, the thickness of the finstock, the fin pitch and the finstock
tube definition, etc. In certain embodiments, the finstock tube
definition is defined, as least in part, by the vertical and horizontal
(e.g., airflow) directional spacing of the coolant channels that span the
airflow (and/or airflow opening). In some embodiments, the finstock tube
definition may include the number of distinct channels or circuits, the
total number of coolant carrying channels extending across the airflow,
or width of the exchanger door, for example, and the number of coolant
carrying channel portions extending across the airflow. Like with the
non-variable parameters, in certain embodiments, the variable parameters
may be defined as numerical or other discrete, manipulatable data
corresponding to the parameter(s).

[0119] In one embodiment, data corresponding to the non-variable
parameters and the variable parameters is obtained by a computer, such as
computer 1800 depicted in FIG. 18. Computer 1800 may include a central
processing unit (CPU) 1802, memory 1804, input/output devices or
interfaces 1806 and a system bus 1808 interconnecting the components. In
certain embodiments, the optimization method disclosed herein may include
utilizing one or more input/output devices 1806 of the computer 1800 to
input the variable and non-variable parameters, and/or data corresponding
thereto.

[0120] Another preliminary step in the process includes obtaining boundary
conditions 1706 in which the heat exchanger will need to operate within.
By way of example, the boundary conditions may be conditions relating to
a system in which the heat exchanger is to be installed. As another
example, the boundary conditions may be specified minimum, maximum, or
like conditions the heat exchanger is to encounter in use. The step of
obtaining boundary conditions 1706 may include recording, selecting,
identifying, inputting or otherwise establishing boundary conditions for
the to-be-optimized heat exchanger. For example, if the heat exchanger is
an air-to-coolant heat exchanger, the boundary conditions may be one or
more of a temperature of the airflow passing across the heat exchanger,
the volumetric flow rate of the airflow across the heat exchanger, the
temperature of the coolant entering the heat exchanger, the volumetric
flow rate of the coolant received by the heat exchanger and/or the heat
load of the environment in which the heat exchanger is installed, etc.
The heat load (including heat loss, or heat gain) may be the amount of
cooling (heat gain) needed to maintain a desired temperature.

[0121] In certain embodiments, several boundary conditions may be
obtained. For example, the boundary conditions may represent the likely
worst case scenario of conditions for the heat exchanger (i.e., the
harshest condition or conditions), the likely best case scenario of
conditions for the heat exchanger, the likely typical conditions for the
heat exchanger and conditions therebetween. As another example, a series
of boundary conditions may be obtained wherein the individual boundary
conditions differ. As described above with respect to the non-variable
and variable parameters, the boundary conditions may be defined as
numerical or other discrete, manipulatable data.

[0122] A further step in the process includes defining desired optimized
and limiting performance metrics 1708 of the heat exchanger. The
performance metrics may be measureable characteristics, capabilities,
conditions or the like related to the functioning of the heat exchanger.
The desired optimized performance metrics may be the performance metrics
of the heat exchanger which the non-variable and variable parameters
optimize, and the limiting performance metric may be used to narrow the
potential combinations of non-variable and variable parameters.

[0123] Defining the desired optimized and limiting performance metrics
1708 may include recording, selecting, identifying, inputting or
otherwise establishing one or more desired optimized and limiting
performance metrics of the heat exchanger. For example, if the heat
exchanger is an air-to-coolant heat exchanger, the desired optimized
performance metrics and the limiting performance metrics for a particular
boundary condition may be one or more of heat removal of the heat
exchanger, air side pressure drop of the airflow flowing across the heat
exchanger, coolant side pressure drop of coolant passing through the heat
exchanger, core weight of the heat exchanger, or one or more metrics
relating to the flow distribution between coolant channels of the heat
exchanger. In one embodiment, the desired optimized (or to-be-optimized)
performance metrics comprise the heat removal of the heat exchanger and
the air side pressure drop of the airflow across the heat exchanger. In
such an embodiment, the heat removal rate and air side pressure drop are
optimized by selecting a combination of variable and non-variable
parameters for the boundary conditions that lead to a maximum heat
removal with a minimum air side pressure drop. In certain embodiments,
the limiting performance metrics may comprise the core (or total) weight
of the heat exchanger, the water side pressure drop of the coolant
passing through the heat exchanger or one or more metrics relating to the
flow distribution between coolant channels of the heat exchanger. as with
the above parameters, the desired optimized and limiting performance
metrics may be defined as numerical or other discrete, measurable data.

[0124] Once the non-variable parameters, variable parameters and boundary
conditions are obtained, and the optimized and limiting performance
metrics are defined, the performance metrics may be obtained 1710 for
possible heat exchanger configurations for the boundary condition(s) with
differing combinations of the variable and non-variable parameters.

[0125] The performance metrics for the possible heat exchanger
configurations with differing combinations of the variable and
non-variable parameters for each boundary condition may be obtained, at
least in part, through the use of a computer, such as computer 1800 of
FIG. 18. For example, the processor may be programmed to utilize the
different combinations of the variable and non-variable parameters and
the boundary conditions of the possible heat exchangers to derive the
performance metrics for multiple (or even each) parameter and boundary
condition combination. As another example, the performance metrics for
the possible heat exchanger configurations for each boundary condition
may be obtained, at least partially, from external the computer (e.g., by
another computer, by a 3rd party, experimentally, etc.) and provided
to the computer and/or fetched by the computer. In some embodiments, the
performance metrics for the possible heat exchanger configurations for
the boundary conditions may be obtained sequentially. For example, in
certain embodiments, the performance metrics for the possible heat
exchanger configurations for a first boundary condition may be
determined, then for a second boundary condition, and so on. In another
example, the performance metrics for a first possible heat exchanger
configuration for the boundary conditions may be determined, then a
second possible heat exchanger configuration for the conditions, and so
on.

[0126] Continuing with FIG. 17, in addition to defining 1708 and obtaining
1710 the performance metrics for the possible heat exchanger
configurations with differing combinations of the variable and
non-variable parameters for each boundary condition, secondary
determinative or instructive performance metrics for the possible heat
exchanger configurations for each boundary condition may also be defined
and obtained. Similar to the performance metrics, the secondary
performance metrics for the possible heat exchanger configurations may
include the heat removal rate of the heat exchanger, the air side
pressure drop of airflow flowing across the heat exchanger, the coolant
side pressure drop of coolant passing through the heat exchanger, core
weight of the heat exchanger and one or more metrics relating to the flow
distribution of the coolant flow between coolant channels of the heat
exchanger. In certain embodiments, the secondary performance metrics may
be defined and obtained in any of the ways that the performance metrics
are defined and obtained, such as those discussed above.

[0127] Once a performance metric of a possible heat exchanger
configuration is obtained, the possible heat exchanger configuration may
be filtered or analyzed 1712 with respect to an acceptable threshold or
limit of the limiting performance metric, as shown in FIG. 17. In one
embodiment which includes the coolant side pressure drop as a limiting
performance metric, the acceptable threshold or limit of the coolant side
pressure drop may be the pressure drop limit of particular connections,
such as quick connections to the inlet and/or outlet manifolds, at a
particular coolant flow rate. This limiting performance metric may be
used to filter unacceptable or unwanted possible heat exchanger
configurations from the pool of possible heat exchanger configurations
used to determine the optimized parameters. For example, if the
performance metrics of a heat exchanger configuration are obtained, and
are not within the acceptable threshold for the limiting performance
metric, then the heat exchanger configuration can be eliminated from
consideration. In this way, the limiting performance metrics and the
associated acceptable thresholds can be used in a filtering step that
streamlines the method 1700. A computer may be used to perform, at least
in part, the comparing the performance metrics with the corresponding
acceptable limits and/or the filtering of the possible heat exchanger
configurations that include a performance metric outside of the
acceptable limit for at least one boundary condition.

[0128] Once the desired performance metrics for the possible heat
exchanger configurations for each boundary condition are obtained, and
the possible heat exchanger configurations are filtered based on the
limiting performance metrics, the step of determining 1714 which of the
possible heat exchanger configurations optimizes the at least two
performance metrics for the boundary conditions can be performed to
determine at least one combination of the non-variable and variable
parameters that optimize the performance metrics for the heat exchanger.

[0129] In certain embodiments, several features of the possible heat
exchanger configurations may be utilized to determine which configuration
optimizes the desired performance metrics for the boundary conditions.
For example, the maximization of a first desired performance metric in
combination with the minimization of a second desired performance metric
may be preferable. In such embodiments, the combination of non-variable
and variable parameters that resulted in the best possible heat exchanger
that maximizes the first desired performance metric and minimizes the
second desired performance metric for the boundary conditions may be
determined. As noted, in one embodiment, the heat removal may be desired
to be maximized and the air side pressure drop minimized. The particular
weight given to each desired optimized performance characteristic may
vary and depend on a host of considerations.

[0130] In certain embodiments, additional performance metrics above the
limiting and desired optimized performance metrics may be utilized or
considered in determining which heat exchanger parameter configuration
best optimizes the defined performance metrics for the boundary
conditions. For example, the secondary performance metrics discussed
above may be utilized or considered in addition to the limiting and
desired optimized performance metrics. In such embodiments, one or more
of the secondary performance metrics may be the same as one or more of
the limiting performance metrics. For example, although a particular
limiting performance metric of a possible heat exchanger configuration
was within the corresponding threshold of the limiting performance
metric, and therefore the possible heat exchanger configuration was not
"filtered out" of consideration, the limiting performance metric may be
used as a secondary performance metric in determining which heat
exchanger parameter configuration optimizes the desired performance
metrics for the boundary conditions. Therefore, in such embodiments, the
optimization method may, in essence, be determining which heat exchanger
parameter configuration optimizes the desired performance metrics and one
or more additional secondary performance metrics for the boundary
conditions.

[0131] In certain embodiments, consideration or use of at least one
secondary performance metric may be considered an additional step, or
part of the step, of determining a heat exchanger parameter configuration
(i.e., combination of variable and non-variable parameters) that
optimizes the desired performance metrics for the boundary conditions. As
an example, the combination of non-variable and variable parameters that
resulted in the possible heat exchanger that maximized the heat removal
performance metric, minimized the air pressure drop performance metric
and minimized at least one of weight, or cost of the heat exchanger, or
heat exchanger core depth, for the boundary conditions may be determined
as the combination of the non-variable and variable parameters (i.e.,
heat exchanger parameter configuration) that optimizes the desired
performance metrics for the boundary conditions of a heat exchanger. The
particular weight given to each desired performance characteristic and
secondary performance metric may vary and depend on a host of
considerations. For example, a first heat exchanger parameter
configuration achieving 1% more heat removal than a second heat exchanger
parameter configuration may not be deemed "optimized" over the second
heat exchanger parameter configuration if it is considerably more
expensive, heavy or thicker than the second heat exchanger parameter
configuration.

[0132] In one embodiment, one or more computers (such as the computer 1800
of FIG. 18) may be used in, at least in part, determining 1714 (FIG. 17)
which heat exchanger parameter configuration(s) (i.e., combination of
variable and non-variable parameters) optimizes the desired performance
metrics for the boundary conditions. For example, the computer may obtain
the performance metrics and the secondary performance metrics for the
different heat exchanger parameter configurations for each boundary
condition and, based thereon, determine the heat exchanger parameter
configuration that best optimizes the performance metrics, for example,
in consideration of any secondary performance metrics, for the boundary
conditions.

[0133] By way of further example, shown in FIG. 19, a computer may obtain
the possible heat exchanger parameter configurations and the performance
metrics thereof for one or more boundary conditions, and any other
requisite or relevant data, and produce one or more visual indications
(e.g., graphs) of the relationship of the different combinations of the
non-variable and variable parameters and the at least two performance
metrics of the possible heat exchangers in the boundary condition. In the
example shown in FIG. 19, a graph displays the performance metrics (e.g.,
heat removal and air side pressure drop) and the variable parameters (fin
type, number of rows of coolant channels in the airflow direction) differ
from the eight designs. The variable parameter fin densities are
indicated by the four symbols of each line indicating the different
parameter configurations, with 10 fins/in being the symbol in the lower
left and 16 fins/in being the symbol in the upper right. Other parameters
besides the variable parameters of the heat exchanger configurations were
assumed to be fixed (i.e., non-variable parameters) in this illustration.

[0134] The graph of FIG. 19 can assist a designer in determining which
combination of variable parameters (fin type, number of rows of coolant
channels in the airflow direction and fin density) and non-variable
parameters best maximize, for example, heat removal while minimizing air
side pressure drop (i.e., optimize the desired performance metrics) for a
particular boundary condition. In this way, charts like that of FIG. 19
can be created for each boundary condition, and the charts for each
boundary condition can be used together to determine which combination of
non-variable and variable parameters optimizes heat removal and air side
pressure drop (i.e., maximizes heat removal and minimizes air side
pressure drop) for the boundary conditions.

[0135] FIGS. 20A & 20B depict another example of a graph useful in
determining a combination of variable and non-variable parameters of a
heat exchanger that optimize performance metrics for given boundary
conditions. In these figures, wherein FIG. 20B is a partially enlarged
version of FIG. 20A, the optimum values of fins/inch and fin thicknesses
are illustrated for heat exchangers with a particular number of rows of
coolant channels in the airflow direction for different combinations of
variable and non-variable parameters. The graph of FIGS. 20A & 20B can be
constructed using data from the optimization method described above, or
portions thereof. For example, the optimization method can be used to
obtain the fin density and fin thickness for optimized heat exchanger
configurations with a particular number of coolant channel columns in the
airflow direction in combination with differing variable parameters.
These fin densities and fin thicknesses can therefore be considered
optimized fin densities and fin thicknesses. The maximum and minimum
optimized fin densities and fin thicknesses can be plotted on a graph to
show the boundaries of the optimized fin densities and thicknesses for
the heat exchanger configurations with a particular amount of coolant
channel rows transverse the airflow direction. Any combination of fin
density and fin thickness lying within the boundary is there an optimized
fin density and fin thickness (i.e., an optimized parameter) of the heat
exchanger with that particular number of coolant channel columns
transverse the airflow direction (and the combination of non-variable and
variable parameters used to create the graph). This process can be
repeated for heat exchanger configurations with different amounts of
coolant channel columns transverse to the airflow direction, such as
shown in FIGS. 20A & 20B. Thereby, the graph of FIGS. 20A & 20B can be
used to conjointly select an optimized combination of number of columns
of coolant channels transverse the airflow direction, fin density, and
fin thickness (i.e., conjointly select parameters that optimize
particular performance metrics) of the heat exchanger.

[0136] Those skilled in the art should note that one or more of the
above-described steps, or a portions thereof, may be performed or
completed without the aid of a computer. In one embodiment, one or more
of the above-described steps, or portions thereof, may be performed
physically. For example, at least one of the performance metrics
(desired, limiting, secondary, etc.) of the differing combinations of the
variable and non-variable parameters for the boundary conditions may be
determined experimentally.

[0137] Further, as will be appreciated by one skilled in the art, control
aspects of the present invention may be embodied as a system, method or
computer program product. Accordingly, aspects of the present invention
may take the form of an entirely hardware embodiment, an entirely
software embodiment (including firmware, resident software, micro-code,
etc.) or an embodiment combining software and hardware aspects that may
all generally be referred to herein as a "circuit," "module" or "system".
Furthermore, control aspects of the present invention may take the form
of a computer program product embodied in one or more computer readable
medium(s) having computer readable program code embodied thereon.

[0138] Any combination of one or more computer readable medium(s) may be
utilized. The computer readable medium may be a computer readable signal
medium or a computer readable storage medium. A computer readable signal
medium may be any non-transitory computer readable medium that is not a
computer readable storage medium and that can communicate, propagate, or
transport a program for use by or in connection with an instruction
execution system, apparatus or device.

[0139] A computer readable storage medium may be, for example, but not
limited to, an electronic, magnetic, optical, electromagnetic, infrared
or semiconductor system, apparatus, or device, or any suitable
combination of the foregoing. More specific examples (a non-exhaustive
list) of the computer readable storage medium include the following: an
electrical connection having one or more wires, a portable computer
diskette, a hard disk, a random access memory (RAM), a read-only memory
(ROM), an erasable programmable read-only memory (EPROM or Flash memory),
an optical fiber, a portable compact disc read-only memory (CD-ROM), an
optical storage device, a magnetic storage device, or any suitable
combination of the foregoing. In the context of this document, a computer
readable storage medium may be any tangible medium that can contain or
store a program for use by or in connection with an instruction execution
system, apparatus, or device.

[0140] In one example, a computer program product may include, for
instance, one or more computer readable storage media to store computer
readable program code means or logic thereon to provide and facilitate
one or more aspects of the present invention.

[0141] Program code embodied on a computer readable medium may be
transmitted using an appropriate medium, including but not limited to
wireless, wireline, optical fiber cable, RF, etc., or any suitable
combination of the foregoing.

[0142] Computer program code for carrying out operations for aspects of
the present invention may be written in any combination of one or more
programming languages, including an object oriented programming language,
such as Java, Smalltalk, C++ or the like, and conventional procedural
programming languages, such as the "C" programming language, assembler or
similar programming languages. The program code may execute entirely on
the user's computer, partly on the user's computer, as a stand-alone
software package, partly on the user's computer and partly on a remote
computer or entirely on the remote computer or server. In the latter
scenario, the remote computer may be connected to the user's computer
through any type of network, including a local area network (LAN) or a
wide area network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet Service
Provider).

[0143] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of methods,
apparatus (systems) and computer program products according to
embodiments of the invention. It will be understood that each block of
the flowchart illustrations and/or block diagrams, and combinations of
blocks in the flowchart illustrations and/or block diagrams, can be
implemented by computer program instructions. These computer program
instructions may be provided to a processor of a general purpose
computer, special purpose computer, or other programmable data processing
apparatus to produce a machine, such that the instructions, which execute
via the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.

[0144] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other programmable
data processing apparatus, or other devices to function in a particular
manner, such that the instructions stored in the computer readable medium
produce an article of manufacture including instructions which implement
the function/act specified in the flowchart and/or block diagram block or
blocks.

[0145] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other devices
to cause a series of operational steps to be performed on the computer,
other programmable apparatus or other devices to produce a computer
implemented process such that the instructions which execute on the
computer or other programmable apparatus provide processes for
implementing the functions/acts specified in the flowchart and/or block
diagram block or blocks.

[0146] The flowchart and block diagrams in the figures illustrate the
architecture, functionality, and operation of possible implementations of
systems, methods and computer program products according to various
embodiments of the present invention. In this regard, each block in the
flowchart or block diagrams may represent a module, segment, or portion
of code, which comprises one or more executable instructions for
implementing the specified logical function(s). It should also be noted
that, in some alternative implementations, the functions noted in the
block may occur out of the order noted in the figures. For example, two
blocks shown in succession may, in fact, be executed substantially
concurrently, or the blocks may sometimes be executed in the reverse
order, depending upon the functionality involved. It will also be noted
that each block of the block diagrams and/or flowchart illustration, and
combinations of blocks in the block diagrams and/or flowchart
illustration, can be implemented by special purpose hardware-based
systems that perform the specified functions or acts, or combinations of
special purpose hardware and computer instructions.

[0147] In addition to the above, one or more aspects of the present
invention may be provided, offered, deployed, managed, serviced, etc. by
a service provider who offers management of customer environments. For
instance, the service provider can create, maintain, support, etc.
computer code and/or a computer infrastructure that performs one or more
aspects of the present invention for one or more customers. In return,
the service provider may receive payment from the customer under a
subscription and/or fee agreement, as examples. Additionally or
alternatively, the service provider may receive payment from the sale of
advertising content to one or more third parties.

[0148] In one aspect of the present invention, an application may be
deployed for performing one or more aspects of the present invention. As
one example, the deploying of an application comprises providing computer
infrastructure operable to perform one or more aspects of the present
invention.

[0149] As a further aspect of the present invention, a computing
infrastructure may be deployed comprising integrating computer readable
code into a computing system, in which the code in combination with the
computing system is capable of performing one or more aspects of the
present invention.

[0150] As yet a further aspect of the present invention, a process for
integrating computing infrastructure comprising integrating computer
readable code into a computer system may be provided. The computer system
comprises a computer readable medium, in which the computer medium
comprises one or more aspects of the present invention. The code in
combination with the computer system is capable of performing one or more
aspects of the present invention.

[0151] Although various embodiments are described above, these are only
examples. For example, computing environments of other architectures can
incorporate and use one or more aspects of the present invention.
Additionally, the network of nodes can include additional nodes, and the
nodes can be the same or different from those described herein. Also,
many types of communications interfaces may be used.

[0152] Further, a data processing system suitable for storing and/or
executing program code is usable that includes at least one processor
coupled directly or indirectly to memory elements through a system bus.
The memory elements include, for instance, local memory employed during
actual execution of the program code, bulk storage, and cache memory
which provide temporary storage of at least some program code in order to
reduce the number of times code must be retrieved from bulk storage
during execution.

[0153] Input/Output or I/O devices (including, but not limited to,
keyboards, displays, pointing devices, DASD, tape, CDs, DVDs, thumb
drives and other memory media, etc.) can be coupled to the system either
directly or through intervening I/O controllers. Network adapters may
also be coupled to the system to enable the data processing system to
become coupled to other data processing systems or remote printers or
storage devices through intervening private or public networks. Modems,
cable modems, and Ethernet cards are just a few of the available types of
network adapters.

[0154] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the
invention. As used herein, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprise" (and any form of comprise, such as "comprises" and
"comprising"), "have" (and any form of have, such as "has" and "having"),
"include" (and any form of include, such as "includes" and "including"),
and "contain" (and any form contain, such as "contains" and "containing")
are open-ended linking verbs. As a result, a method or device that
"comprises", "has", "includes" or "contains" one or more steps or
elements possesses those one or more steps or elements, but is not
limited to possessing only those one or more steps or elements. Likewise,
a step of a method or an element of a device that "comprises", "has",
"includes" or "contains" one or more features possesses those one or more
features, but is not limited to possessing only those one or more
features. Furthermore, a device or structure that is configured in a
certain way is configured in at least that way, but may also be
configured in ways that are not listed.

[0155] The corresponding structures, materials, acts, and equivalents of
all means or step plus function elements in the claims below, if any, are
intended to include any structure, material, or act for performing the
function in combination with other claimed elements as specifically
claimed. The description of the present invention has been presented for
purposes of illustration and description, but is not intended to be
exhaustive or limited to the invention in the form disclosed. Many
modifications and variations will be apparent to those of ordinary skill
in the art without departing from the scope and spirit of the invention.
The embodiment was chosen and described in order to explain the
principles of the invention and the practical application, and to enable
others of ordinary skill in the art to understand the invention through
various embodiments and the various modifications thereto which are
dependent on the particular use contemplated.

Patent applications by Eric A. Eckberg, Rochester, MN US

Patent applications by Howard V. Mahaney, Jr., Cedar Park, TX US

Patent applications by International Business Machines Corp Corporation US